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Computer Cases

Computer cases can be split into two major groups. ATX cases are for mainstream and workstation computers, while mATX and mini-ITX cases are used for weaker, smaller and more power-efficient configurations, sometimes with laptop components.
As you can see the standard ATX computer case structure is very simple, all components have unique compartments.

The back of the case houses the power supply on top (usually sold together with the case).

Under the power supply is the motherboard with I/O ports exposed through the back panel. Unfortunately more and more systems are built with mATX motherboards, so the space below the motherboard is usually wasted. Main board manufacturers are to blame for this, they managed to install two PCI-Express 16X slots on the small mATX motherboard format, so even for hardcore gaming PC’s there’s no need for full-sized ATX motherboards.

5.25” storage devices are installed in front of the power supply, usually 4 such bays are available that have openings on the front panel. The most popular such devices are DVD burners and/or Blu-Ray readers, combos or writers. 3.5” bays are usually filled with standard desktop hard drives. Although there are usually 1-2 bays that have front panel openings there’s no important component to install there, other than a memory card reader. A long time ago 3.5” floppy disk drives were mandatory, that’s why these bays are still available on ATX computer cases.

There’s one more very important feature of the computer case: it has to allow air to pass through, so the internal components can stay at normal temperatures. A typical mainstream computer doesn’t need any additional fans, the power supply sucks out enough air, but for more professional systems with 2-4 graphics cards and top processors fans must be installed in the front, the back, and sometimes even on the sides.

These are a bit exaggerated examples, but powerful systems may require such cooling solutions.

Mini-ITX cases usually contain minimalist computer configurations. The example above is an exception, because it supports one full-sized graphics card, while most such cases support only one low-profile expansion card, and in very rare cases does the motherboard support a PCI-Express 16X card. Most mini-ITX boards are designed with a PCI or PCI-Express 1X slot that supports tv-tuners, network cards or other low transfer rate components.

Although these mini-ITX enclosures have very little space inside, it seems that they are spreading quickly, and becoming more and more popular. Manufacturers already introduced mini-ITX cases with 150Watt power supplies that can support more performance. An AMD low-power quad core processor consumes 45Watts at full load, while a discrete graphics card stays below 60W. About 45watts are left for the other components, enough for a desktop hard disk, 2x2GB memory and a laptop optical drive.