Motherboards are where all parts meet.
Everything inside the system unit connects to the motherboard.
Again, form counts! The most common form factors for motherboards
(same as cases) are Micro-ATX and ATX. Baby AT is still around but
becoming harder to find by the minute.
If you want to upgrade
your motherboard or install a new one in the system you are building make
sure all of your parts match the slots/sockets. If your motherboard
has a socket 370 processor slot you must use a socket 370 processor (There
is a socket 370 adapter for slot 1 motherboards). If the motherboard
has only 3 PCI slots you can only mount 3 PCI devices. If you have
an ISA device, then the new motherboard must have an ISA slot. Study
the motherboard specifications carefully. Make a note of any KNOWN
incompatibilities. For instance, some Socket 370 motherboard support
"Coppermine" Celeron processors, but not "Tuelatin" Celeron
Typical ATX socket 370
Motherboards commonly have some components built
in, like the sound sub system. You can add one of your own most of
the time. Just be sure to purchase a sound card if sound is not
built in. Use the PC hardware
list to ensure
that you have everything you need if you are scratch building a new