Choosing the Correct Case

The choice of a case is more than a mere matter of aesthetics, as it must be able to dissipate the hot air generated inside it. But how can we know that a case is suitable for a given computer?

Take a look at Figures 3 and 4. They show an actual computer having trouble from overheating. To the point, with the case closed, the computer jammed. When we removed the cover, the problem disappeared. Examining carefully the placing of the processor and the size of the power supply unit, the reason for overheating became clear: in the first place, there is hardly any space between the power supply and the processor’s fan, preventing the processor’s hot air from being suitably dispelled. In the second place, we can see that the segment of the supply above the processor has no slots for dissipating the air coming from the processor. Thirdly, the bottom of the power supply has no holes for dissipating the heat generated by other computer internal components (video card, motherboard chipset, hard disk, etc). Although the power supply’s side is slotted – in front of the case’s 5 ¼” bays – these are obviously insufficient to remove the hot air from inside the computer.

CaseFigure 3: The CPU cooler is too close to the power supply!

CaseFigure 4: Check how the power supply prevents the hot air coming from the CPU to be dissipated.

There are several solutions to this problem, but the most suitable and easy way is changing the computer’s case. Upon buying a new case, examine the size of the power supply, checking that the new unit does not covers the processor’s fan, as happens in the above case (even a medium size tower case can be used to avoid covering the processor’s fan by the power supply). Other possible solutions are just changing the power supply unit or even drilling holes in the metal panel of the part of the power supply facing the processor (in the latter case, the power supply should be demounted and the holes drilled with the panel off the supply, in order to avoid bits of metal falling into the supply when drilling, as this could later cause a short circuit when the computer is switched on).

Studying better this story, we found out that the case is an old model, revamped by upgrading a cartridge-type Pentium III processor. This case may have been very good for a cartridge type processor, but it is not good for newer CPUs. Although the motherboard fits perfectly in an old case, this does not mean that the case is suitable for the heat dissipation required by newer components. Therefore, be careful when upgrading to new computers reusing older cases.

Also it is a good habit to organize the cables inside the case using cable holders whenever possible. The computer in Figure 4 is a mess, the cables are preventing the correct airflow inside this computer, helping the overheating situation.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.