[GRLUG] Motherboard Questions

[networkman@triton.net]

> Hey guys I have a few easy questions.
<snip>
> 1.)  Will a flex ATX fit in an ATX case?  O.K. I know it will fit,
> being smaller, but are the screw patterns compatible.  I seem to have
> a lot of screw holes that I am not using in my generic case.

It *should* fit okay; FlexATX(9" x 7.5")is a relative of microATX, the
latter being a little larger at 9.6" x 9.6".  FlexATX boards generally
will fit into microATX cases without any problem, and since many microATX
boards will mount in regular ATX cases, it's a good be the Flex board will
too.

If you should find that not all of the screw holes line up, you can always
substitute in some plastic offsets to support the board.

> 2.) Is the power supply compatible.

With a few exceptions, ATX/microATX/FlexATX motherboards all have the same
20pin ATX connector; some motherboards also have an addition 12v 4pin
connector as well - usually for boards designed for P4 processors.  If you
should find that your power supply doesn't have the 4pin P4 connector(and
your motherboard needs it) you can get an adapter online such as this:

http://www.xpcgear.com/p412volt.html

> 3.) Generic power question - If the cpu is a low power cpu and doesn't
> use even close to the 300 watts rated on the power supply does the
> power supply pull 300watts from the from the wall or will it pull only
> what is needed?

First off you need to know that computer power supplies are rather
inefficient, generally about 65%.  So for every 100watts input, you're
only getting 65 to the output.  So your example of 300watts really only
gives you about 195 watts on the input side.  That said, unless you've got
a system with multiple harddrives, optical drives, case fans, etc. you're
going to be fine with the 300 watt unit - probably even a 250 watt would
be okay.  If you've only got a single hard drive, cdrom drive and floppy,
then you can get by with less; which is why you may have seen
"low-profile" or SFF PCs with very small supplies on the order of 80 to
145 watts.  Bear in mind though that if you plan to do any upgrades such
as adding additional drives, a larger power supply will allow for that
growing room. :)

Hope that helps!

Rich