System unit - what is it?

The main place in the entire computer system, not counting the monitor, belongs to the system unit, in which, in fact, the entire main stuff is located in the form of “iron” components. What is the system unit of the computer, how it is arranged and what kinds it is, now and will be considered. Separately, it will be said about "systemists" for lovers of modern computer games and multimedia.

System unit: what is it?

First, pay attention to the interpretations offered by most dictionaries and other resources. In the most general understanding of the system unit - this is the computer, or rather, its main part, if you do not take into account the monitor. It is in it that all the main “iron” components of the computer system are concentrated. And all peripheral (external) devices are connected to it.

the system unit is

The blocks themselves according to device type, form factor and size can be divided into several main types, which will be discussed separately.


In the meantime, look at the appearance.When you first look at the case, if you do not go into the internal device, you can immediately notice that on the front panel there are several basic elements that are present on any “system unit”. This is a power on / off button, a reset button (Reset), LED indicators in different numbers (the hard disk access indicator is always there), slots for installing removable hard drives and CD / DVD-ROM devices. Previously, you could also find FDD drives, but now flexible media (floppy disks) are not used.

computer system unit

Sometimes there may also be several USB ports, and in some cases even audio outputs can be noticed. Behind the grid, you can see installed coolers (cooling fans), connectors for connecting the power supply and monitor, and on the motherboard wall - all the other sockets, the number of which depends on the types of installed devices (video, network, sound, printer, etc.) ).

In addition, special chassis may be present below for the convenience of moving the unit from place to place (for vertical models).

The main types of system units

As is already clear, the system unit is a case with all the stuffing built into it.But the arrangement of elements inside it directly depends on its type.

To date, you can find blocks of horizontal (Desktop) and vertical (Tower) type. Monoblocks in which the monitor and the system unit itself are made as a monolithic structure are separately distinguished.

gaming system unit

Desktop blocks appeared earlier and are now used either in very old models of computers, or in ultramodern ones. They are classified into four types:

  • dimensions 533 x 419 x 152 mm - Desktop;
  • dimensions 406 x 406 x 152 mm - FootPrint;
  • dimensions 406 x 406 x 101 mm - SlimLine;
  • dimensions 381 x 352 x 75 mm - UltraSlimLine.

which system unit

But the most widespread still got the "towers". By type, form factor and size they are divided as follows:

  • MiniTower - dimensions 178 x 432 x 432 mm;
  • MidiTower - dimensions 183 x 432 x 490 mm;
  • BigTower - dimensions 190 x 482 x 820 mm;
  • SuperFullTower - bigger proportions than BigTower, and MicroTower - smaller sizes than MiniTower.

There is a legitimate question: what is the reason for such a variation in size? It all depends on what kind of equipment can be installed in such a case. In addition, there is still a lot depends on the type and form of the motherboard, video card and many other factors.

ATX Form Factor

Now let's see which system unit is the most popular today.Of course, this body, made in the ATX form factor, which is a kind of vertical structures.

how to connect the system unit

In fact, the design can be defined as a kind of universal standard applied to the size of motherboards, the shape and location of certain connectors, the geometric dimensions of the case, the mounting position of the power supply and its electrical characteristics, etc.

Device system unit

Now a few words about how blocks of any type are arranged. The main elements here are power supplies, coolers, motherboards and hard drives. With power and cooling, I think, everything is clear.

device system unit

For Winchesters, special designs are used, sometimes called pockets, into which they are inserted and fixed with screws.

But the motherboard is the most significant element, since it is connected to all the rest of the "iron" (hard drives and drives for optical media including). On the "motherboard" installed processors, memory bars, graphics, sound and network adapters. There are also special slots and connectors for connecting the keyboard, mouse,external devices such as printers, modems, gaming components, external wireless communication modules, removable media through the appropriate ports, specialized telemetry tools, and any other equipment manufactured for modern computer systems.

Connecting the main elements of the computer

Now let's see how to connect the system unit to the power supply and monitor, and also attach the most necessary components to it.

the system unit is

For power supply, there is a standard socket on the back wall into which the power supply cord is inserted. As for the connection of equipment, it, as already mentioned, is made exclusively through the motherboard. For this purpose, slots are used in which devices can be inserted or, as in the case of hard disks or optical drives, the connection is made using universal loops. For monitors, an integrated or discrete video adapter can be used, which are also located on the motherboard. But for processors there are connectors called sockets.

Interestingly, any connector, cable or slot meets a specific connection standard, which eliminates the possibility of connecting an incompatible device to the motherboard.For example, installing a video card in the slot for the sound adapter will fail.

Game and multimedia system units

Separately worth seeing what is a gaming system unit. As a rule, such blocks are called gaming solely because of the powerful configuration, although now they can be distinguished even by the non-trivial version of the case, the color scheme, the presence of illumination, etc. The manufacturers clearly have enough imagination.

computer system unit

As for the configuration, the gaming system unit is a set of almost the most modern "iron" devices, including powerful processors, graphics accelerators and embedded audio systems, large amounts of RAM, etc. Motherboards are usually, unlike standard models have specific connectors for attaching additional controls such as joysticks, steering systems for racing and much more. But here, as it is considered, SSD-drives that have a higher speed of reading and writing information on them must be used as a device for storing information.And the issues of installing discrete graphics cards and rails of the latest generation and monitors with diagonals of about 24 inches are not discussed at all, because without this, it will be impossible to achieve normal performance and detail in modern computer games with their increased demands on the hardware.

Somewhat lower requirements for systems designed to work with multimedia. For graphics and video, you need a good monitor and a video card, for sound processing, a corresponding audio system (preferably an external type), etc.


This is the classification and standard device of modern "systemists". Monoblock computers were not considered here, since they are quite expensive, which is still an obstacle for their mass distribution. In addition, to get to the main "iron" components in them is much more difficult if you compare this process even with laptops.

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