Types of cases and power supplies of the PC system unit. Cases and Power Supplies Types of PC Cases and Power Supplies

Users pay insufficient attention to choosing the right power supply for them. As a rule, power supplies that are part of Chinese system units are purchased or on a residual basis - for delivery. This approach is not justified, since it is the power supply unit that is responsible for supplying power to the system components. Experience shows that most users realize the importance of purchasing a high-quality power supply in each specific case quite late, when they already have to replace burned-out system components. We should not forget that 75% of system unit freezes are caused by either the software or the installed power supply.

Modern market computer components offers users a wide selection of different products at affordable prices. First of all, these are cheap domestic and Chinese power supplies. A distinctive feature of these devices is the use of cheap components, the concomitant replacement of many power elements with conventional conductors, and the absence of any passive cooling. The latter circumstance forces manufacturers of cheap power supplies not to worry about fan speed, since only a fan operating at maximum speed is capable of cooling these devices without radiators to dissipate heat. The use of simplified power circuits in power supplies irreversibly leads to a decrease in the stability of voltages on the device lines.

Any modern power unit for a personal computer must produce three key voltage lines: 12 volts, 5 volts and 3.3 volts. The meaning of this or that line has changed over the past decade and is reflected in the ATX specifications. The first power supplies met the ATX 1.xx specification, which required the power supplies to supply the main load on the 5 volt line. This circumstance was due to the fact that power to the central processors was provided through this voltage line.

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Over time, specifications have emerged ATX 2.xx, which require power supplies to provide the main load via a 12-volt line. This is due to the fact that all the main components of the system unit are powered from this power line of the device. Power for all modern processors and video cards is provided through this line. In modern power supplies, the load on the 5-volt line comes from the motherboard, storage devices and various drives.

Voltage line at 3.3 volts traditionally used by the motherboard to provide power to the RAM strips in the system unit. The absence of any stability along the 3.3 volt line irreversibly leads to undermining the stability of the entire system, which is manifested either by the entire system freezing or by a blue screen followed by a reboot.

Modern specifications allow some voltage deviation on any of the three lines. According to the latest data, these deviations should not exceed 15%. This is a fairly significant figure, but the motherboard must ensure stable operation of system components during such voltage dips or increases. As a rule, the use of expensive motherboards from well-known manufacturers allows users to not notice the defectiveness of their power supplies for a long time. Over time, motherboard capacitors outlive their service life, and all system components become quite sensitive to the slightest drops and rises in voltage, especially along the 3.3 volt line.

A distinctive feature of Chinese and domestic cheap power supplies is the "swing" phenomenon. The “swing” phenomenon is that when the load on the 12 volt line increases, this voltage drops with a parallel increase in the voltage on the 5 volt line. The opposite trend is observed when a load of five volts appears on the line. This circumstance is due to the simplicity of the power supply circuit of cheap power supplies. This does not mean that these power supplies cannot be used - they can be used, but only wisely. It is necessary to try to maintain a load balance on both voltage lines - 12 and 5 volts. This will extend the life of your cheap power supply and extend the life of your system components.

Availability of such phenomenon easy enough to identify. To do this, you need to turn on the system unit and find four contacts in the four-pin Molex connector to assess the voltage level on the 12 and 5 volt lines. The red line and ground are five volts. The yellow line and ground are twelve volts. As a rule, the power supply always has one free Molex connector, so you can test the voltage level directly with a parallel computing load.

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If power unit It does not hold one of the lines confidently enough and we can talk about a drawdown of about 0.5 volts from the nominal values ​​- you should think about replacing the power supply.

It should be remembered that level testing power supply voltage must be carried out exclusively with a multimeter or voltmeter. All BIOS measurements, which are sometimes presented by various software products, are only suitable for assessing voltage drops, but not for assessing their exact values.

There is a known difficulty in checking voltage level on line 3.3 Volt. As a rule, you have to limit yourself to the data provided by the motherboard BIOS or make a parallel connection to the 24-pin power supply connector connected to the motherboard. The pinout of this connector is shown in the figure below:

Second category power supplies are high-quality devices from renowned manufacturers. It should be understood that the power supply packaged in a cardboard or colorful box is not a device from a reputable manufacturer. Many power supply manufacturers practically do not resort to packaging their solutions and sell OEM versions of their solutions - without any packaging.

Modern quality power supplies have sufficient weight, which ranges from 1 kg and above. The weight of the power supply largely depends on its power. You should pay attention to the thickness of the steel of a high-quality power supply. In a high-quality device, the case wall does not bend under finger pressure, while on cheap devices, holes form that cannot be straightened.

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Some more expensive power supplies are retrofitted with a modular power management system, which helps to more intelligently arrange system components in the system unit. Cheap power supplies are practically not equipped with this system, as this significantly increases the final cost of the product.

Upon purchase power supply It should be remembered that each power supply has active cooling using the installed power supply. Many users follow modern trends and want to purchase a power supply with the largest possible cooling fan. In many cases this is justified, especially when the cooling system is equipped with a PWM speed controller. Experience shows that this should not be a reason to refuse power supplies with 80 mm cooling fans on the front wall. Many well-known manufacturers produce devices with this cooling system, since during light loads on the power supply the fan makes much less noise than 120 or 140 mm solutions on the bottom wall of the device.

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An undoubted advantage power supplies With fans on the bottom wall, heat is removed from the processor power system. However, it should be understood that this effect is not always possible, since many system units require power supplies to be placed on the bottom wall. And decent power supplies with an 80 mm cooling fan on the bottom wall have grilles through which hot air is drawn in from the area of ​​the processor power system.

Presented brief review should help our users decide on purchasing a power supply for their solution. Remember, how long your computer will serve you largely depends on its power source.

The most popular printer models are divided into 3 types: matrix, inkjet and laser. Let's look at each of these three types of printers in more detail.

With this article I begin a series of posts about a personal computer, since this topic is quite extensive, and we will start from the very basics; we will have to read a lot. And I, in turn, will try to present the material in a clear and at the same time interesting way. Be patient, and when we reach the finish line, no one will dare call you a “teapot.”

Let's start with the system unit, or as advanced users call it “system unit”, and we use the old fashioned “processor”. It looks like a small box, inside of which there is a bunch of all sorts of wires, devices and much more that is not clear, which in computer language is called hardware. This is where we will begin to deal with it.

The standard minimum set of any system unit usually consists of:
1. power unit
2. CPU + cooler
3. Video card
4. RAM modules
5. Hard disks
6. Optical drive
7. System (motherboard) board.
Now let's take a closer look at each element separately.

Power unit.

This is one of the most important elements of the system unit, since without power, all electronic components become just a bunch of hardware, so take its choice seriously. The figure shows a standard power supply that is installed in all system units.

It is located at the top of the system unit, and is designed to convert 220V AC voltage into DC voltage, which is necessary for the computer to operate. From the outside into the connector (2) power cord is connected 220 volt, and from the inside there is a bundle of wires coming off it (5) already with the required voltage 3.3, 5 and 12 volts, at the end of which there are connectors (5) , designed to connect internal components of a computer.

Switch (1) you can turn on or off the power supply, fan (4) It takes air into the system unit through its standard openings in the case, and, throwing it out of the system unit, promotes additional mixing of the air flow inside the computer, simultaneously cooling its radio components. Switch (3) Designed to switch incoming voltage 110 or 220 volts. I strongly do not recommend trying to switch it, you won’t get away with breaking one power supply, by default everything is as it should be.

And now, actually power supply connectors:
1 — the main voltage is supplied to the motherboard;
2 — is an auxiliary connector for powering the processor and is installed on the motherboard;
3 — peripheral devices such as old optical drives or IDE hard drives are powered, as well as through attachments (6) additional power is supplied to the video card depending on the computer configuration;
4 — designed for connecting FDD drives, so-called “floppy drives”;
5 — powers devices with SATA interface (hard drives, optical drives).

I hope you have already figured out why you need a power supply with all its wires and connectors. Now let's talk about such an important parameter of power supplies - power.

Today, the minimum power for computer power supplies is 450-500 watts. These figures are taken by summing up the energy consumption of each element included in the computer, and of course a 30% power reserve, and where would we be without it. There should always be a margin of safety. What if, over time, you want something more powerful or faster, and this is not excluded, which means that the load on the power supply will increase, but there is no reserve. What? Right. Let's run to the store.

For an average home gaming computer, the power should be about 600 Watts; it simply doesn’t make sense to take less, but you shouldn’t get carried away with increasing it either. Why overpay for something that may not be in demand. A good quality block today costs at least 80 - 130 dollars, I don’t see any point in taking it for less, as you might end up with a fake.

Let's say there are two power supplies that are absolutely identical in all respects, only their prices are different, the question naturally arises, what is the difference? From personal experience I will say that when you are repairing radio equipment, and as soon as you look inside, you can immediately see the quality of the assembly of this or that device. Chinese engineers are very good at reducing the cost of equipment design, but at the expense of reliability and operating time.

If there are jumpers on the board instead of half of the radio components, or there is nothing at all where it should be, and the use of parts with underrated parameters leads to their rapid wear and, consequently, failure. Such a power supply will work, but at the limit of its capabilities, due to insufficient load capacity, but its primary task is to reliably provide power to all computer components. As a rule, when cheap models fail, they take more than half of the computer with them. So, when choosing a power source, choose only reputable brands, for example InWin, FSP, CoolerMaster, Hiper. You can always find reviews and tests of these power supplies on the Internet and navigate them.

And one more piece of advice. When choosing a case, and they usually come with built-in power supplies, be sure to ask the seller, or see for yourself what the power of the installed unit is. If it is lower than calculated, ask to replace it with a more powerful model. The main parameters are indicated on the side of computer power supplies, in the figure I have highlighted them with rectangles. The upper rectangle shows the model and power of 430W, and the lower rectangle, as you guessed, includes input-output voltages, load current for each voltage and power.

And most importantly, a high-quality power source is, first of all, the key to the health and stability of your home computer: don't skimp on food.

The power supply is the most important component of any personal computer, on which the reliability and stability of your build depends. There is quite a large selection of products on the market from various manufacturers. Each of them has two or three lines or more, which also include a dozen models, which seriously confuses buyers. Many people do not pay due attention to this issue, which is why they often overpay for excess power and unnecessary bells and whistles. In this article we will figure out which power supply is best for your PC?

A power supply (hereinafter referred to as PSU) is a device that converts high voltage 220 V from an outlet into computer-friendly values ​​and is equipped with the necessary set of connectors for connecting components. It seems to be nothing complicated, but upon opening the catalog, the buyer is faced with a huge number of different models with a bunch of often incomprehensible characteristics. Before we talk about choosing specific models, let’s look at what characteristics are key and what you should pay attention to first.

Main parameters.

1. Form factor. In order for the power supply to fit into your case, you must decide on the form factors, based on from the parameters of the system unit case itself. The dimensions of the power supply in terms of width, height and depth depend on the form factor. Most come in the ATX form factor, for standard cases. In small system units of the microATX, FlexATX, desktops and others, smaller units are installed, such as SFX, Flex-ATX and TFX.

The required form factor is specified in the characteristics of the case, and it is by this that you need to be guided when choosing a power supply.

2. Power. The power determines what components you can install in your computer, and in what quantities.
It is important to know! The number on the power supply is the total power across all of its voltage lines. Since the main consumers of electricity in a computer are the central processor and video card, the main power line is 12 V, when there are also 3.3 V and 5 V to power some components of the motherboard, components in expansion slots, power drives and USB ports. The power consumption of any computer along the 3.3 and 5 V lines is insignificant, so when choosing a power supply for power, you should always look at the "characteristic" power on line 12 V", which ideally should be as close as possible to the total power.

3. Connectors for connecting components, the number and set of which determine whether you can, for example, power a multiprocessor configuration, connect a couple or more video cards, install a dozen hard drives, and so on.
The main connectors, except ATX 24 pin, are:

To power the processor, these are 4 pin or 8 pin connectors (the latter can be detachable and have a 4+4 pin entry).

To power the video card - 6 pin or 8 pin connectors (8 pin is most often collapsible and is designated 6+2 pin).

For connecting 15-pin SATA drives

Additional:

4pin MOLEX type for connecting older HDDs with an IDE interface, similar disk drives and various optional components such as rheobass, fans, etc.

4-pin Floppy - for connecting floppy drives. They are very rare these days, so such connectors most often come in the form of adapters with MOLEX.

Extra options

Additional characteristics are not as critical as the main ones in the question: “Will this power supply work with my PC?”, but they are also key when choosing, because affect the efficiency of the unit, its noise level and ease of connection.

1. Certificate 80 PLUS determines the efficiency of the power supply unit, its efficiency (efficiency factor). List of 80 PLUS certificates:

They can be divided into the basic 80 PLUS, on the far left (white), and the colored 80 PLUS, ranging from Bronze to the top Titanium.
What is efficiency? Let's say we are dealing with a unit whose efficiency is 80% at maximum load. This means that at maximum power the power supply will draw 20% more energy from the outlet, and all this energy will be converted into heat.
Remember one simple rule: the higher the 80 PLUS certificate in the hierarchy, the higher the efficiency, which means it will consume less unnecessary electricity, heat less, and, often, make less noise.
In order to achieve the best efficiency indicators and obtain the 80 PLUS “color” certificate, especially at the highest level, manufacturers use their entire arsenal of technologies, the most efficient circuitry and semiconductor components with the lowest possible losses. Therefore, the 80 PLUS icon on the case also speaks of the high reliability and durability of the power supply, as well as a serious approach to creating the product as a whole.

2. Type of cooling system. The low level of heat generation of power supplies with high efficiency allows the use of silent cooling systems. These are passive (where there is no fan at all), or semi-passive systems, in which the fan does not rotate at low powers, and starts working when the power supply becomes “hot” under load.

When selecting a power supply, you should pay attention to for the length of the cables, the main ATX24 pin and the CPU power cable when installed in a case with a bottom-mounted power supply.

For optimal installation of power wires behind the rear wall, they must be at least 60-65 cm long, depending on the size of the case. Be sure to take this point into account so you don’t have to bother with extension cords later.
You need to pay attention to the number of MOLEX only if you are looking for a replacement for your old and antediluvian system unit with IDE drives and drives, and even in a significant quantity, because even the simplest power supplies have at least a couple of old MOLEX, and in more expensive models There are dozens of them in general.

I hope this small guide to the DNS company catalog will help you in such a complex issue at the initial stage of your acquaintance with power supplies. Enjoy the shopping!

The case of the system unit of a desktop personal computer contains: a motherboard with expansion cards, storage drives and a power supply. The type, size and placement of the motherboard used, the minimum power of the power supply and the maximum number of installed drives depend on the type of system unit case. Mounting (installation) places, or compartments for drives can be of two types - with external and internal access. Access to drives mounted in mounting locations of the latter type can only be achieved with the system unit case cover open.

Currently, there are two standard sizes of drives in use: 5.25 inches wide (CD-ROM drives, some hard drives) and 3.5 inches wide (disk drives, hard drives). The actual width of 5.25- and 3.5-inch devices is slightly larger than 5.25 and 3.5 inches. Their name is historically due to the dimensions of drives for 5.25- and 3.5-inch floppy disks. The number, location and standard size of drive bays largely determine the consumer qualities of the computer case.

Horizontal cases include desktop, small-footprint (low-profile), slimline (thin, slender) and (ultra) superslimline (ultra-compact) cases. The motherboard in these cases is also located horizontally. A desktop case usually has two 5.25-inch and one or two 3.5-inch bays with external access.

Cases with a vertically positioned motherboard resemble a tower in appearance and are usually presented in three varieties: mini-tower, midi-tower and big-tower, which usually differ from each other in the number of 5.25-inch bays with external access (2, 3, 4 or more), dimensions and power of the installed power supply, and therefore the ability to install additional expansion cards and drives.

One of the most common cases for a personal computer is a mini-tower case. It typically has two 5.25-inch and 3.5-inch bays with external access, two 3.5-inch bays with internal access, and contains a 200-watt power supply. A mini-tower case can accommodate a standard set of drives and expansion cards. Wider expansion possibilities are provided by the midi-tower case (three 5.25 and two 3.5-inch external and three to four 3.5-inch internal bays, a more powerful power supply). Big-tower cases are used for network servers, contain one or more power supplies with a power of more than 300 watts and have the widest expansion options. Slim cases usually have a weak power supply (90-100 watts) and no more than one internal and one external compartment, which makes upgrading a PC in such a case problematic.

As a rule, on the case of the system unit there are several buttons for controlling the computer (Reset, Turbo), LED and digital indicators of operating modes (Turbo, Power, HDD, frequency), a lock for locking the keyboard (Lock), a built-in speaker and a power switch (Power). ).

Cases from different companies may differ slightly in design and dimensions.

There are special cases for multimedia computers, equipped with stereo speakers and audio output controllers. For comfortable operation, low-noise cases are available, which use power supplies with low-noise fans.

Frame sizes AT and ATX

The type, internal dimensions of the case and the power supply used depend on the motherboard used. Currently, there are several case sizes that are incompatible with each other - the old AT standards (for desktop and tower cases) and LPX (for slim cases) and the new ATX (desktop and tower) and NLX (slim) standards proposed by Intel. They differ both in the size and location of the motherboard, and in the voltage ratings generated by the power supplies.

ATX cases are characterized by easier access to the internal components of the computer, improved ventilation inside the case, the ability to install a larger number of full-size expansion cards, and advanced power management capabilities. This standard may not be particularly relevant for work, but for overclocking it is simply irreplaceable. Not only because the cooling of the elements has become better, but also because it has become easier to change memory or get to the processor. A good mother needs a good body.

Which case should you choose? First, you must determine for yourself whether you need ease of getting into the case or not? If not, then a regular case for $30 with the ability to install an additional fan will suit you. You will assemble the computer, close it and this case will not torment you anymore.

What's wrong with such cases? Firstly, the metal is very thin, which means the shielding is worse and the mechanical strength is lower. If you are going to buy a Desktop and put a monitor on it, then you can forget about cheap cases - it will bend under the weight of a 15" monitor, and a 17" one will not stand at all. Secondly, you will cut your hands on sharp edges, breaking out stubborn plugs. The cheaper the case, the less convenient it is for assembly. The power supply will hang over the board, the hard drive will menacingly approach the memory, the noisy turntable will drive you crazy at night.

Form factor (how to choose a case).

For hundreds of years, philosophers argued about what was more important - form or content, and finally agreed that these categories are in dialectical unity (and, at the same time, in continuous struggle, as the leader of the world proletariat would note). At the computer level, this very unity consists in the fact that the “content” (the motherboard with the processor and controllers) is installed in the “form” (the case), and they must correspond to each other. And the struggle is manifested in the fact that both technical (manufacturability, ventilation) and ergonomic (appearance, noise insulation, etc.) requirements for the design of the case and, accordingly, for the design of the motherboard are gradually changing.

Just a couple of years ago, there were practically no options for desktop PCs - the SOHO market was monopolized by AT-type boards and cases. There are two main types of desktop PCs available today - AT and ATX. So it makes sense to think about which one to choose for a new computer or when upgrading?

As you know, a computer system unit consists of a case in which a power supply, built-in storage devices (disk drives, CD-ROMs), several buttons and lights, a small speaker (“beeper”) and, of course, the main element for which it was all assembled are installed - motherboard.

The main sizes (form factors) of desktop motherboards are AT, ATX with mini-ATX and micro-ATX varieties, and NLX. The latter type was introduced by Intel in 1997 as the most technologically advanced standard (in it, controllers are installed parallel to the motherboard through an adapter called a riser card, which is convenient for assembly and repair), but until now NLX has practically not gained popularity. Other types of boards are actively competing in the market.

As for cases, they are also divided by standard sizes into AT and ATX with a variety of micro-ATX. Each type has its own power supply, also called AT or ATX. These sources have different capabilities (ATX is smarter, understands processor commands, so it can, say, turn off the power when the OS shuts down), and completely different connectors for connecting to the motherboard.

Thus, not every board will fit a particular case, and vice versa. The table shows the sizes of motherboards and their compatibility with cases and power supplies.

As can be seen from the table, for each form factor of motherboards the width is constant, but the length can vary. For example, different models of AT boards may have dimensions of 250x220, 230x220, etc. However, all boards of the same type fit into their respective cases due to the standard position of the external connectors and mounting holes. True, in the ATX family there are as many as ten standards for the location of external connectors, of which three are widely used, so ATX case manufacturers often supply several different decorative strips for the rear panel.

In addition to the types of cases listed in the table, there are also combined AT/ATX cases into which you can install any motherboard. However, they are structurally more complex and significantly more expensive, and therefore are not widely used.

The AT form factor appeared during the transition from eight-bit PC models to sixteen-bit ones, that is, when the IBM PC XT was replaced by the IBM PC AT, the name of which reflected the use of the new form factor. At first, most of the models were horizontal, “lying” (desktop), but gradually the “standing” vertical version (tower) completely took over the initiative, and today the desktop case is a rarity. Motherboards from the second to the fifth generation, that is, from the 286SX to models for Pentium, K6, M2, fit perfectly into the AT, so no other form factors were required for the PC.

ATX appeared later, so we can confidently say that it is a more progressive design, which corrected some of the inherent shortcomings of AT and took into account new, increased technical and technological requirements. At first, ATX models were significantly more expensive than AT, which is why they were not widely used. But gradually the situation leveled out, and today ATX not only actively competes with AT in the market, but is also beginning to gradually displace it. I will provide statistical data on the percentage of manufactured models of motherboards of different types for processors of the fifth (Pentium, K6, M2 for Socket7 connector) and sixth (Pentium II/III for Slot1/2 connector and Celeron, M3 in a PPGA package for Socket370 connector). The statistics were compiled from the “Modern Computer Technology” reference book, which contains information about more than 800 modern models.

As you can see, for each of the three main classes of processors (Pentium, PentiumII/III and Celeron) there is its own most common form factor. And if AT is the undisputed leader for fifth-generation processors, then in the sixth generation its popularity has decreased significantly. Many serious manufacturers (including Intel, Chaintech, SuperMicro, Tekram and others) believe that AT is not suitable for motherboards for Slot1 at all, which is why they do not have a single AT motherboard for PentiumII/III in their range. The leader among boards for Celeron is the micro-ATX form factor, but this does not mean that for such boards it is necessary to purchase a micro-ATX case: you can also use the more universal ATX, which can accommodate all varieties of this family.

Now let's look at the main differences between the form factors. As for the appearance of the cases, the difference is almost unnoticeable, even if you put them side by side: the standard ATX (mini-tower) is only a centimeter higher, two centimeters wider and three deeper than the AT. However, this small increase in size allows for an important advantage: on ATX motherboards, the Slot1 connector for the PentiumII/III processor is placed along, rather than across, the board, which, along with increasing the internal volume of the case, significantly improves ventilation.

The ATX power supply, unlike the AT source, has a command interface, which allows you to implement all the power management and energy saving functions included in modern boards (ACPI standard).

On AT motherboards, the position of the keyboard connector and the line of slots for connecting cards—device controllers—are standardized. In ATX and micro-ATX, connectors for a mouse, printer, USB bus, COM ports, midi/joystick, as well as audio and video devices, if they are integrated on the motherboard, were added to this list. This increases the reliability of the system compared to AT, where signals for most external devices are output from the board to the rear panel via short adapter cables, and, as is known, plug-in connections are a significant source of failures due to poor (oxidized, loose) contact. In addition, adapters often occupy a position on the rear wall reserved for a slot, which reduces the possible number of installed controllers.

On ATX boards, unlike AT, miniature PS/2 type connectors are used to connect the keyboard and mouse. They have a number of disadvantages: firstly, they are the same and can be confused, and secondly, the PS/2 mouse should not be reconnected while the power is on - this can damage the chip in the mouse itself or on the motherboard. True, the disadvantages of the PS/2 mouse can be easily eliminated: those who like to switch on the go can use a regular mouse in ATX, connecting it via a serial channel, as in AT. But for many, something else is more important: the PS/2 mouse does not occupy a COM port, so both serial channels installed on the motherboard remain free for connecting external devices. All other types of connectors used in ATX are exactly the same as in AT.

Now about the prices. ATX and micro-ATX motherboards themselves, if they are more expensive than AT boards with similar parameters and quality, are not much more expensive. Mice and keyboards cost almost the same. The case itself is somewhat more expensive - for the simplest ATX you will have to pay five to ten dollars more than for AT.

We cannot give a definite answer to the question here: which standard size is right for you, and whether the advantages of the ATX form factor are worth the money you need to pay extra for it. For a specific configuration, salespeople in our sales areas will help you find this answer. And the main goal of this review is to show that, unlike the situation one or two years ago, there is now real competition on the market between AT and ATX and the choice, as they say, is yours.

The power supply (or power supply) is usually mounted and supplied with the system unit case for which it is intended. The power of the computer's power supply must fully, and even with some margin, ensure the energy consumption of all devices connected to it. The more devices that can be installed in the system unit, the more power the power supply must have. On average, the power of power supplies varies from 90 to 150 watts for low-profile and desktop PCs and up to 200-330 watts for mini-tower and big-tower. Some of the units operate in low consumption mode (70-75 watts), which meets the requirements of the Energy Star program. Modern units use low noise fans.

On the case of a typical power supply of an IBM PC-compatible computer, as a rule, there are one or two cooling fans, a power switch (or a connector for it), a network voltage switch (for 220 and 110 V), a general network connector, a network connector for connecting a monitor , power cables with connectors for the motherboard and drives. Some power supplies also have an external fuse holder. To connect to the motherboard, two six-pin connectors are usually used (less often one common). Four-pin connectors are used to power the drives. These connectors differ in size: large style and small style. If there are not enough connectors, you can use special Y-splitters.

Based on the voltage ratings generated and design features, power supplies are divided into blocks for AT-cases and blocks for ATX-cases. AT blocks produce +5V, -5V, +12 and -12V DC, have a mechanical switch and are connected to the motherboard using two identical six-pin connectors (if connected independently, they can easily be confused with the most disastrous consequences for the motherboard).

ATX blocks, in addition to the ratings listed above, also produce a voltage of 3.3V and are connected to the motherboard via a 20-pin connector, eliminating the possibility of incorrect installation. In addition, ATX blocks, as a rule, do not have a mechanical switch. When connected to the electrical network, they are in a state of reduced consumption (standby), from which they can be turned on by pressing an electronic switch on the case, or by a software command in response to some external event. For example, this could be a command over the network (this function is called wake on LAN) or a telephone call received and processed by the modem. Switching to standby state can also be done programmatically.

Power problems

Statistics show that for reasons related to power failures, in 75% of cases information is lost and in 65% the electronic equipment itself fails, so a stable power supply to computers is of particular importance. An essential point when equipping an office is the correct wiring of power lines (220 V). All components of a personal computer and peripheral equipment connected to it must be powered from one phase of the electrical network. Tires must be made radially with one common point. To disconnect computer equipment, a separate switchboard with circuit breakers and a general switch must be used. In addition to a complete shutdown of the mains voltage, problems in the computer's power supply can arise due to its short-term dips, overvoltages, harmonic distortions, and various electromagnetic and radio frequency noise. To avoid such troubles, you should use special protection devices.

The consequence of a sudden power outage of the computer (regardless of its cause) can be a complete loss of data in RAM and cache memory, and when working in a network operating system, the collapse of file allocation tables on the disk is likely. In the worst case, damage to the electronic components themselves may occur. The same consequences can be caused by short-term supply voltages within a fraction of a second (Sags, or Brownout) and a (time-variable, but not periodic) decrease in supply voltage (Rolling Brownout). Sometimes in the network there is a short-term increase in the supply voltage for a fraction of a second (Surge) and a pulse increase with an amplitude of at least 100% of the nominal (Spike), which can damage the computer’s switching power supplies.

Under the influence of strong electrical noise generated either by the operation of electrical machines (Electro Magnetic Interference (EMI) or the operation of radio-emitting devices (Radio Frequency Interference (RFI), the waveform of the sinusoidal supply voltage can be seriously distorted, which usually leads to hardware failures ( Glitch) and errors when executing programs.

To ensure uninterruptible power supply to your computer, various uninterruptible power supplies are used.

The simplest protection for a computer's power supply is usually provided by so-called surge suppressors. These devices protect the powered computer components from various surges and surges in the power supply voltage, as well as radio frequency noise (see Power supply problems).

A higher level of protection is provided by normalization devices, which reliably supply voltage from all kinds of noise and allow it to be adjusted over a fairly wide range. When these devices use ferroresonant conversion technology, they can provide complete galvanic frequency isolation, preventing the penetration of high-frequency noise into the load circuit.

The ferroresonant transformer also provides excellent protection against voltage surges, surges and surges in the supply network. Most of the damage to system, modem, fax-modem and network cards is a consequence of high voltage pulses entering the interface port not through the power supply, but through data cables. To avoid such unpleasant effects, it is necessary to use additional devices.

Only a device called a UPS (uninterruptible power supply) or UPS (Uninterruptible Power Supply) can ensure the computer operates during a complete blackout. Functionally, such a device consists of an interference suppression device, a charger, a battery and a voltage converter (inverter). On the domestic market, the most famous UPS companies are APC, Exide Electronics, MGE and ViewSonic. All UPS currently offered can be divided into several groups.

The smallest group includes the so-called built-in (Internal) UPS. This is the cheapest and simplest type of uninterruptible power supply. Structurally, this device looks like a separate expansion card, inserted into the corresponding connector on the computer motherboard, or as a device for installation in a free 5.25-inch drive bay.

The largest group of UPSs consists of devices operating using On-Line (always on) and Off-Line, or Standby (standby) technology. A subgroup of devices made using Line-Interactive technology (interactive UPSs) looks somewhat isolated, although most often such devices are classified as Standby (or Hybrid) UPS. Always-on UPSs provide a stable power supply to connected devices regardless of the state of the power grid, while backup UPSs switch to battery mode only when the external supply voltage is turned off and are therefore characterized by a certain finite switching time. One of the main differences between interactive UPS is the presence of a Smart-Boost node, which allows, in the event of short-term voltage dips, not to switch to battery power, but to increase the input voltage.

For local area networks, automatic monitoring of the status of the UPS connected to the server is of great importance. For this purpose, special programs are included in network operating systems, and the UPSs are either equipped with appropriate control boards (UPS Monitoring Board) or initially have the ability to exchange data with a computer via a serial port.

Basic parameters of the UPS

The choice of the most suitable UPS model is influenced by many parameters, the most significant of which are the level of protection, the power of the device, its operating circuit, the shape of the output voltage, etc.

If the protected device does not contain data that could be lost when the power is turned off, or it is needed only occasionally (for example, a diskless terminal, scanner, modem or printer), then a high-quality Pilot-type surge protector will be a sufficient level of protection for it. For a computer on which important work is performed, and even more so for a local network server, a UPS is mandatory. You should never connect a laser printer through a UPS due to the high power it consumes during operation.

Typically, the power of a UPS device is specified in volt-amperes, which should be divided by approximately 1.5 to convert it to watts.

It is recommended that the power of the UPS be at least 15-20% greater than the total power of the devices connected to it. To protect a simple office or home PC with a 14-15-inch monitor, a 200-450 VA UPS is sufficient; for a powerful home multimedia computer with a 17-19-inch monitor, a 400-750 VA UPS is required, and to protect a local network server you may need UPS from 750 VA to several kVA.

The Off-Line source switches from mains power to battery power when the mains voltage parameters increase beyond permissible limits, but is powerless against low voltage cases common in our networks. In domestic conditions, the most effective source is Line-Interactive, which contains a voltage stabilizer and switches to batteries only when the mains voltage goes beyond all conceivable limits (usually the voltage range of 80-260 V is still considered working). There are also On-Line sources in which the input voltage is converted into direct battery current, and then a sinusoidal voltage is generated based on it. It is usually used only for devices that are particularly critical to the quality of power, since due to constant operation on batteries it has lower efficiency and battery life and is significantly more expensive.

Uninterruptible power supplies allow you to adjust the shape of the output voltage from purely sinusoidal (which is required to operate an inductive load, for example, a transformer) to almost rectangular, which is acceptable for equipment with switching power supplies (computers and peripherals). All UPSs use rechargeable batteries with a limited service life, depending on the intensity and correctness of their use (this period usually does not exceed 2-3 years). Some UPSs allow you to turn on the devices they serve in the complete absence of voltage in the external network (the so-called), which is especially important if you need to read information from a PC.

The software supplied with the UPS usually allows you to monitor the current state of the voltage in the network, as well as control the stopping and starting of the operating system and applications, as well as turning off/on the computer during voltage fluctuations in the network.

Additional features of the UPS include working as a surge protector for several additional outlets, filtering voltage surges and interference in telephone networks and Ethernet networks, as well as advanced self-monitoring capabilities.

Based on materials: “Big Encyclopedia of Cyril and Methodius”, “Personal Computer from Ador Ya”, “Overclocking”