Aside from how much space the computer takes up, why is this so important?  Actually, because the size has a direct effect on the components within the case.  The full tower case can hold a larger power supply, a larger motherboard (which may mean a larger processor with a larger heat sync and fan), more internal cards and more external bays and ports.  The smaller cases hold less.

 One of the primary restrictions, one that drives most of the other considerations, is the size of the motherboard.  For motherboard form factors, see motherboard.  The chart below shows the limitations on the type of motherboard that can be used inside the various cases:

 Now, let’s consider bays.  Bays are the slots that drives fit into.  They’re for hard drives, disk drives, CD/DVD drives, Zip drives, etc.  Some drives, like the hard disk drive, fit inside the case, and they’re internal.  Others are outside the case, and they’re called external.  As you can see below, there are limitations on the number of both internal and external drives imposed by the case and its motherboard:

 The case and the motherboards will also cause limitations on the number and types of ports, or physical connections, that are available on the computer.  Some cases will have 3, 4 or 6 USB ports in varying (e.g. USB-2, USB-3) combinations, either all in the rear of the case, or perhaps two or more on the front.  Some will have all connections:  USB, maybe also FireWire, maybe even Thunderbolt.  But beware:  Some will not have PS2 ports for the keyboard and mouse (particularly Dell desktop computers, which stopped using them years ago).  Increasingly, many computers will no longer have parallel, firewire or serial ports.  Firewire ports are disappearing on PC (not yet Apple) laptops, while the faster Thunderbolt (a la USB-3) is showing up on Apple laptops.  There is a trend toward more and faster USB ports (the really fast “USB 3” ports are becoming more common on newer boards) in place of these older type ports.  However, if you have older printers which use parallel cables, or special devices (label printers, backup drives, etc.) which use serial cables, keyboards and mice which require PS2 ports or the like, you have to make sure you have that capability, which will be dictated by the case and the motherboard.  Also, check to make sure that the newer operating system required by the newer board will support backward compatible drivers for these ports.  (For example, a board which supports Windows 7 may not have drivers for your old Windows XP hardware, so you won’t be able to backwards install to the Win XP O/s using that board.) Of course, you may be lucky:  For desktops, there are many add-on PCI cards for USB-3, serial, parallel and other ports.  For laptops, the choice is more limited:  There are adaptors to convert between serial, firewire, parallel and USB, and they may suffice.  But be sure to test them first, as they don’t always work as advertised with all devices, depending on hardware and drivers, and you could be taking a chance.

 Finally, there is the matter of the materials that the case is made of.  One of the primary considerations in building a computer is the ability to vent heat from the motherboard, as the chips and other hardware become quite hot.  Most computers these days have at least two (processor and case) and quite often three fans perpetually running.  Aside from the consideration that the computer must be physically placed to maximize the venting of the air pulled from inside the machine, there’s also the matter of building the case out of a material that will keep it cool as well.  Steel is the most common material used to construct cases.  Not only is it strong, it is relatively inexpensive.  Aluminum is even more desirable, as it moves heat more efficiently, but is more expensive.  Acrylic materials may look nifty, but should generally be avoided, as plastic is not a very good heat conductor. And putting those neon lights inside just adds to the heat.

 Now that you’ve got through the choice of your case, you’re ready to purchase the component electronics you’ll want to build your baby.  One thing to consider in this regard:  Some computer cases come with the power supply included.  Power supplies are the devices that convert house current into lower voltage current that can then be applied to the motherboard, other boards and cards, drives, etc.  Power supplies vary in quality and power.  Most of the time, the power supplies that come with the case aren’t the best.  I personally believe that the power supply is an important part of your computer.  A poor one will blow out in the face of power fluctuations, or won’t last for a long time.  If it fails, it may take your motherboard, RAM chips or drive with it.  This can be an expensive repair, one that can be remedied by spending only slightly more on the power supply.  We generally put in a 500 Watt power supply, and usually only from a handful of reputable manufacturers.  That additional twenty or thirty dollars can make a huge difference.

Bet you didn’t know that selecting your computer case was much more than just a cosmetic consideration!

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