2. The Case

I have an old PC that is not working any more, so I will be using pictures {not the best pictures but I am no good with the camera!} of that as it comes apart, so you understand what's going on.

The case or main unit {which houses the computer components/parts: motherboard, CPU, etc.} needs to be chosen carefully. Cooling of your system is an important factor, as well as if your components will actually fit. Ok so lets look at the front of a case first.

The Front

1. Indicator lights for the power and drive activity


2. USB, firewire and audio ports/sockets


3. 2 bays for CD-ROM/DVD drives


4. 2 bays for a floppy disk drive


5. A vent

Note: Not all cases will have the ports/sockets/features I have listed and shown in the picture above, so make sure you select one that has everything you want/need. {You will see the front vent on my computer when i take the PC apart as I go along.}

The drive bay covers {Disk drives} are easy to snap in and out {Although my case has hinged covers that do not need to be removed to gain access to any new disk drive - check yours before breaking it}. The second bay in my PC is not actually in use so I'll get a picture later to show you.

Cases or chassis, are generally metal and have removable panels. The vents are for warm air to flow out of the machine whilst the fans are to suck cool air into and around the machine. It is important not to let them get clogged up with dirt/dust. These are two newer cases with vents and fans in different arrangements:


The Sides


Both sides are the same, they have this one small vent, this was enough five years ago when I bought the computer. But today's PCs need better cooling systems with bigger vents and fans, as we expect more from our technology and internet.

If you are going for a top/new system you should use a Thermally Advantaged Chassis {TAC - This may or may not be used as a real term, I just typed it to make life easier} {or "Prescott Ready", "Chassis Air Guide 1.0/1.1"}. Intel recommend no less than TAC for their Pentium 4 CPU and above {Gaming and high end machines will need this}. As you can see below from Intel's sketch, it has a tube on the inside of the side panel. This is to guide air directly to the motherboard and CPU {I'll write about them later} but for now you should know they are the two most expensive of all the components/parts:


The Back

1. PSU with main fan


2. More sockets/ports


3. Another fan {This is over the motherboard}

Note: Some cases come with a power supply unit {PSU}, but if you are building your own machine you are more than likely going to build a higher powered machine for the same price as a lower powered machine ready built from the shops. So you may want to upgrade the power supply or buy a case without a power supply {we'll talk more about that later}.

The fan/vent openings need to be large like they are. The openings should be 60% or more - {So if you have a fan which has more than 40% of the 'openings' covered by a bit of metal showing the case companies logo, that is not good!} You should go for fans at least 92mm for todays machines, so keep that in mind when selecting a case. Some people cut more openings in their case, but it depends how brave you are.

I will come back to this post once I have taken the PC apart, and show you the inside layout of a case. For now I will explain what else needs to be taken into account when choosing a case.

You need to consider the case's compatibility with the components you will be using.
A term that is used a lot is 'form factor'. This is the size and shape of everything.
So the screw holes in the case need to match up with the screw holes on the motherboard, and everything needs to fit, basically. {The screws and standoffs you need usually come with the case.

Case Form Factors

There are two main form factors: ATX {Advanced Technology eXtended} and BTX {Balanced Technology eXtended}. BTX being the newest. However the ATX form factor remains top for build-it-yourself'ers. Most components {RAM, Power supplies, CPU and other connectors} can be mixed but ATX motherboards are for ATX case's and BTX motherboards are for BTX case's.

I will get a picture of both style cases so you can compare the two layouts, for now here is the inside of my ATX case with all the components still in: