I don't remember if my computer was in sleep mode or it was running when I last walked away from it. When I wanted to use it, it was OFF and pressing the on/off switch had no effect. I tested the power supply with a tester and it was good. When power is connected, the green light on the power supply blinks about once a second when all its connectors are properly connected; since I've not noticed the blinking before, I don't know if it means something or nothing. I'd appreciate any hints on what to do to zero in on whatever failure has occurred. I haven't yet checked the on/off switch, but that's easy and I'll do that.
First suspect would be power supply,next check your ram, next would be a fried motherboard.. I would change the Power supply first, if it still won't do anything, then you are in BAD shape... Motherboard is toast.. If you still want to keep the pc, then you can find another motherboard ...most motherboard start at about $30.00 bucks and up.
Ghostman 1, thanks for responding. My problem was, I think, a Gigabit card that overloaded the power supply (PSU), causing it to fail. My test, using a Thermaltake Dr. Power Supply Tester, indicated the tester was WORTHLESS, since it had the same response to the failed PSU and to an identical (but GOOD) PSU from another computer. However, the good PSU fired up the previously dead computer in a flash. I replaced the dead PSU with one more robust and things are back to normal.
