spooky2th :
Do you have the 8-pin CPU power connecter, connected?
Oh, & yes, the connector is connected. I've tried other power supplies and get the same result
I don't know if this is related but I've run this PC 24/7 for very long periods of time. When I finally did give it a break for a day or two here and there, it would be difficult to boot. The problem started when one of these times, nothing happened. I turned off the power supply and back on and the PC booted fine. Then after a few more times of this it took many times off and on to finally get it going. Then recently it started acting like it wasn't getting enough power when the power switch is turned on. After a few more tries turning on and off the power supply it booted. That has been going on now for months. Now, finally. can't get if going at all. I bought a new power supply and same result. The funny thing is (and this included the old PS) sometimes after doing nothing after trying the power case switch, and right when I turn off the power supply switch, the CPU fan would act like it wanted to come on and then of course. it would die. This happens most of the time now, no matter what power supply I use. CPU, MB?
I'm stumped. I don't want to say this thing is dead because it's the only machine I have with XP still on it and Outlook express..........ah real email client!
One more thing, the CPU has two 4 pin connectors. I've only used one and the other next to it had a cap on it. I took the cap off and have both 4-pin connectors plugged in. The main power is the 20 pin connector. There is also the 4pin connector that is independent & that is almost part of but not part of the 20 pin main power connector. It is also connected like always.