computer won't turn on
Last night I left my computer on when I left for work. When I came home, I found it turned off, I thought it was no biggie, maybe my dad turned it off. But when I pushed the power button to turn it back on, nothing happened. No lights turned on, no fans or anything. I then unplugged everything and opened up the case. I plugged the power supply back in, and tried powering agian. Agian nothing happened. The only light that was on was the standby powerlight on the motherboard.
My intitial reaction is that it's a power supply failure, or a power on switch failure. However looking through some other posts on similar problems says there is a chance it is a motherboard issue.
What can I do to narrow this down to a single problem.