Try disconnecting all usb devices, you tried a different keyboard, so
that clears that one up.
The only other cheap things you can try is re-seating all the cards
(doubt that will help - but 'sod law' say's otherwise).
Re-booting the bios by removing the battery for about three minutes,
but do note the bios will have to be
reset in the bios screen afterwards, so this might be left as a last
desperate attempt.
One good test is to get an optical mouse.... if it lights up
underneath then thats a good sign that the 5 Volt supply is ok for the
keyboard and mouse etc, or you could test the pins for this 5 V supply
with a test meter, being careful not to short any other pins out.
No 5 Volts could suggets either a power supply or mobo fault, not also
that some usb devices may use the supply from the mobo to power them,
a short here could blow a fuse on the mobo, these are in form of a
surface mounted resistor.
The first goal is getting the bios to boot, are you getting the POST
or bios beep.... because if you're not this is your very first goal.
The bios should boot (single beep) and also you'll be able to get into
the bios screen set up with just the RAM, CPU and graphic card
installed... yes the hard drive can also be disconnected, so that's
all these eliminated in one go.
Supposing all is ok at this stage, you'll get the bios beep and then
it will ask you to "insert the disc with the operating system
on" or something to this effect.
So which way you go about it really depends on if you can hear that
single bios beep or not, one common problem is the ol' bios battery
itself guess if it's more than 2 or 3 years old it's worthy of a
swap.
Power supplies can give all sorts of problems, but dashing out for a
new one may not solve it, trying a known good one will prove the
point.
Davy
