Cases and Power Supplies
A computer's case is more than a
box. The case includes the drive cage, the internal compartment that holds disk
drives, and almost always the power supply, among other features, all of which
we discuss in this chapter.
Cases
Most people think of a case as
merely the enclosure that holds a PC together. That view is reasonable for
people who buy a PC and never open the case, but anyone who builds or upgrades
PCs soon realizes that not all cases are created equal. This section describes
what you need to know about cases.
Cases Overview
The computer case is your
computer's housing. You need this to store your components, the largest of
which is your motherboard. A good quality case can have a big impact on the
performance and durability of the computer. Cases sold have to meet
requirements for shielding against both external RFI and interference to
external devices that is generated by the computer.
Good cases are designed to provide
for proper airflow to keep the components from overheating. Well made cases do
not have a thin tinny feel or sound when you tap on them. They have rolled
edges to prevent injury. Panels should fit together well without requiring
excessive effort. When the computer is running, a good case does not make
excessive vibration noises. Other attributes of good cases include ease in
opening and ease in accessing internal components.
Case Components
Cases come with various
components, as shown in below figure.
Most of these components are
self-explanatory. Drive bays are areas in the front for installation of
removable media (CD, DVD, floppy, Zip, etc.). The 5 1/4-inch bays are for all
but the floppy drives. Cases usually come with small speakers, which are there
to provide very basic sounds to the user. About all these speakers play are
warning beeps and the sound of a modem connecting. These speakers are very important,
because multimedia speakers don't work before Windows has booted, if Windows is
in Safe Mode, or if there is a problem with the sound card.
While many older PCs had key
locks, few newer ones do. Locking a computer prevents it from being powered on.
The most important indicator lights are the ones that show that power is on and
that the main hard drive is active. The hard drive indicator is helpful to show
if the hard drive is running too much, or if the computer is locked up. On
recent cases, the only button is the power button. Older cases might have a
Reset button, which simply turns power off and on, and a "Turbo"
button. Leave the Turbo button in the On position unless a tech support
technician tells you to turn it off.
Types of Case
A basic guide to Computer Case
types.
Mini Tower
Advantages: Excellent size which
can be placed on top of below of a computer desk.
Disadvantages: While this case
does offer upgradeability it can be filled up much faster then the Mid-Sized
tower.
Recommendations: Great PC for
end-users and small businesses.
Mid-Size Tower
Advantages: Excellent case which
can fit below and on top of your computer desk. Plenty of expandability for new
devices for businesses, end-users, and advanced users. One of the most used
computer cases found today.
Disadvantages: None
Full-Size Tower
Advantages: Excellent computer for
upgradeability. Excellent case for a server machine.
Disadvantages: Cost is going to be
a lot more then a standard case. Generally A large case which cannot be placed
on top or beneath a desk.
Recommendations: This case is an
excellent choice for all users and businesses.
Desktop
Advantages: Excellent desk
computer. Great use of desk space when monitor is placed on top of the computer.
Disadvantages: With some types of
desktop cases can be very difficult to upgrade. Does not really work on the
floor.
Recommendations: We recommend that
this type of case be purchased by advanced users or users who plan to have a
stand alone machine as a server.
How to Choose a Case
Choosing a computer case can be
difficult if you don't know what your looking for. The range of computer cases
is huge and bigger then its ever been. So how do you find one that suits you.
This guide will explain how to choose a computer case that suits your needs.
When you are choosing one Case you have to consider:
External Space
The first factor to consider is
how much space your PC case is going to take up. Are you placing it on a tight,
crammed desk? Or on a large desk? If you have the space, tower PC cases are a
good choice. If you're short of space, you may wish to consider smaller mini PC
cases which are getting more popular these days.
Internal Space
Another factor to consider is how
many components you wish to fit in your PC case. If you're a computer nut like
me, you'll want to fit in a good motherboard, CPU, a couple of hard drives,
video card, LAN card, cooling fans, a CD-ROM drive and a DVD writer. That's a
lot of components to be cramming into a PC case! Again, a good choice would be
a tower PC case. However, with so many components, you have to watch out for
overheating problems - make sure you deck out the system with a couple of good
fans.
Motherboard Support
Check that your motherboard can
fit into the case! Some cases are flexible enough to support AT, ATX and
Baby-AT boards, but others only support one of these sizes. Even then, you need
to be careful - some cheaper 'ATX' cases don't really fit ATX motherboards. I
remember buying a wonderful ATX motherboard and it couldn't fit into my PC
case!
Power Supply
Most PC cases come with power
supplies. With more and more components being fitted into a PC, you will
certainly need enough juice to power them.
Cooling
If you're a over clocker or have
many system components, you'll need to ensure you've got enough fans in that
case to cool the system. Good PC cases allow multiple cooling fans to be
installed, ensuring good ventilation.
Looks
Just a few years back, PC cases
were boring white boxes. These days, you can find a plethora of colorful PC
cases - if you're concerned about your PC's 'look'. Many PC enthusiasts I know
go for good looking PC cases that come in a variety of colors - red, black,
green, blue and what not.
Power Supplies
A computer power supply is a
compulsory unit to a computer. Without the power supply a computer is useless
as it is just a case full of metal and plastic. This page will explain the
different power cables and connectors and how they work inside your computer.
A power cable connects from the
power point to the power supply where it supply's the motherboard and other
components with power. Often there is a power switch on the back which can be
switched off to stop the power current. If this is not switched off and even
though the computer is off power will still be drawn out of the power point
(very small amount).
The most common power supply that
we have in our computers today are the ATX Power Supply. The AT Power Supply
was found in many computers a few years ago but this has become less common.
The graphic below shows each power cable and its name.
The computer power supply is
placed inside the computer case generally near the top of the case. It is
sometimes necessary to buy a mini power supply for some cases are so small that
they need one. Most computer cases when bought come with a power supply that is
suited to its case. There are usually power ports on the motherboard for the
fans in the case but if not it is possible to buy an adapter that will convert
power from the 4-pin power cable to a fan power cable.
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