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Motherboards
Even if you buy pre-configured computers, you should still consider what
kind of motherboards you are getting. It is very common today to find a number of
the devices, which were formally expansion car, are now integrated into the
motherboard. In many cases, the motherboard is smaller and therefore the total
cost is reduced. However, this means if you wish to use something other than
what indeed motherboard manufacturer has provided for you, you'll need to spend
additional money as well as needed away to disable the device on the
motherboard.
The reason the motherboard becomes smaller is that it can "get
away with" having fewer expansion bus
slots. Since the hard disk controller,
for example, is integrated into motherboard, you do not need to use an expansion
slot for. If this were a controller for IDE
drives, you are less likely to want to buy one your own. However, if the SCSI
host adapter is built and, you want to use something more powerful than the
one which is provided, have to take up of the main expansion slots with the additional
SCSI host adapter.
Another problem motherboard design brings with it is the placement
of the integrated controllers. In some cases, I have found the plugs for such
devices stuck between the expansion slots. While this does a great job of
saving space, it makes it extremely difficult to access the pins. The only way
to connect the cable to the pins was to remove all of the cards. However, you had to
be extremely careful when ypu put the cards back in so as not to pull a cable off
of the pins. Although it is unlikely you will be changing expansion cards every
day, the headache and wasted time often negates any benefit of having paid $10
less for the motherboard.
Most were motherboards which I have encountered,
with three PCI
slots and at least three ISA
slots. Some come with either an
addition PCI
or ISA
slot, while some have an AGP slot. However, you can expect
to have at least six expansion slots makes between PCI
and ISA.
One thing you need to be careful about when shopping for motherboards is whether or not they
support your chosen CPU. People do not often have a CPU before they have the
motherboard (although I did once), you may have decided on a particular CPU
before you buy it and the motherboard.
The days are gone in which you could
simply bought a "PC motherboard" and expected to work with your CPU.
The technology is changing so fast and there are so many different kinds of CPUs on the market,
you need to be absolutely sure the CPU
is compatible with the motherboard. Most
of the motherboard manufacturers have Web sites with a compatibility matrix.
You can find out which CPUs are supported and which clock speeds.
Sockets
One thing to consider when buying in motherboard for your CPU
is where you are going to plug in that CPU.
Not all CPUs are alike and non-all
sockets for the CPUs are alike. As of this writing, nine different socket types
(0-8) have been defined.
|
Socket Designation
|
Number of Pins
|
Pin Layout
|
Voltage
|
CPU
|
OverDrive Processors
|
|
0
|
168
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In line
|
5V;
|
486DX
|
DX2, DX4
|
|
1
|
169
|
In line
|
5V
|
486DX, 486SX
|
DX2, DX4
|
|
2
|
238
|
In line
|
5V
|
486DX, 486SX, DX2
|
DX2, DX4, Pentium
|
|
3
|
237
|
In line
|
3V or 5V
|
486DX, 486SX, DX2,
DX4
|
DX2, DX4, Pentium
|
|
4
|
273
|
In line
|
5V
|
60 and 66 MHz
Pentium
|
Pentium
|
|
5
|
320
|
Staggered
|
3V
|
Other Pentium
|
Pentium
|
|
6
|
235
|
In line
|
3V
|
DX4
|
Pentium
|
|
7
|
321
|
Staggered
|
3V
|
Other Pentium
|
Pentium
|
|
8
|
387
|
Staggered
|
3V
|
Pentium Pro
|
Pentium Pro
|
There area several things to note about this table. First, There was never
an officially designated socket 0, but Intel made a line of socket for 486
OverDrive processors which followed the Socket 0 design.
Second, the
difference between an in-line and staggered pin layout is simply whether or not
the pins line up in different rows.
The inner 169 pins of Socket 2 match
those of socket 1, so you can simply plug in a CPU
that is normally intended for
Socket 1. The only difference is that the outer pins are open.
You will see
that Socket 3 is the same size as Socket 2, but has one pin missing and the
"keying pins" are in different place. It supports CPUs with either 3V or 5V and
the rearranged keying pins help prevent someone from accidentally putting a 3V
CPU into a 5V machine.
Socket 4 was for the first Pentiums, but is no
longer used. It was followed by the Socket 5, which had a staggered pin layout.
Socket 6 had a similar layout to sockets 2 and 3, but was only able to handle
the 486DX4.
Finally, we get to Socket 7, which is currently the most common
for Pentium based machines. The Pentium Pro CPUs fit into Socket 8.
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