I use the same mobo...

Could I suggest try a couple of things, try unplugging the power cord
for 2 minutes or so and then try rebooting. if that dosen't help..
then removing the bios back up battery could help, but
doing this will set the bios to its default settings and would have
to be reset these in the bios set up screen afterwards.
You'll get no boot up if this 3 volt battery is duff
so swapping it 'may be' the best approach this only fit's one way of
course.

As you say the power supply could also be the cause... you'll get bios
boot with just the CPU, RAM and graphic card connected, so it could be
any of these items and indeed the mobo.

What happens is when you press the power button the bios does a quick
test known as POST (Power On Self Test) if ok it'll give that single
ok bleep, then hands over control to the CPU and the CPU then orders
the hard drive to load windows and any start up programmes into RAM..
and away you go.

For some strange reason one GA7VA I have, if I have a power cut or
disconnected the main power cord (ie switch off) I have to go through
a little routine to get it to boot...

I have to apply the main power press the power button, then unplug or
swutch off the main power and then 'presto' it boots up at the second
attempt... as though the 'power good signal' is too fast for the
power supply. See this flow chart which may also help-:


[b:55946c45d9]Computer diagnosis charts - PSU, Hard drive & Cd Rom
etc[/b:55946c45d9]
http://www.fonerbooks.com/ide_hd.htm and a after thought make sure the
fans are running especially the Northbridge, which is a small gold one
near the CPU, I think all GA-7VA has these and look out for these-:
[color=blue:55946c45d9]
[b:55946c45d9]Bad cap's in mobo's[/b:55946c45d9][/color:55946c45d9]
http://home.earthlink.net/~doniteli/index27.htm these are taken from
the sections of 'Computer help desk' on HTFC and the link for this is
http://www.howtofixcomputers.com/bb/viewforum.php?f=48

Davy