One of my computers is a Hewlett-Packard dx7500 Microtower that I bought on clearance at an unbelievable price about three years ago. I'm running Windows XP Pro, Vista Business x86, and Netrunner 12.12 on it. With an add-on graphics card, it serves mainly (and 24/7) as a participant in a distributed-computing (DC) project, but I've also used it to get a taste of both Linux and XP.
A couple of days ago, the computer -- at the time running on Vista -- finished a stage in the DC project and I rebooted into XP to see what updates (Windows Defender, MS Office) there might be waiting for it. I installed the updates and left it on overnight, as usual.
The next morning I went into my office and noticed that the computer was turned off. Nobody other than me goes into the office, so I knew that no living being had shut it down. It used to go off and not come back on after a power outage, but for several months now I've had it on a UPS battery so it should not have turned itself off even if the power had gone out (which it had not, in any event).
I hit the power switch as normal. Imagine my surprise and alarm when -- nothing happened!! No matter how hard, how many times, or for how long I pressed the switch, it would not come on. Time for Web research and diagnostics.
I plugged the power cord into a different outlet. Didn't help.
I opened the case and dusted it. (There WAS a lot of dust inside. ) No dice.
I removed the graphics card. Still nothing.
Changed out the CMOS battery. Nada.
The only sign of life the PC is giving, is that the green LED at the back of the case, up where the power supply is located, is still glowing. The glow seems to be fainter than it used to be, but I can't be sure of that. However, nothing else seems to be doing anything: neither the fans nor the hard drive appear to be spinning up. There is no POST and no beeps.
My Web research seems to point to either the power supply or the motherboard. Two questions:
1. Is there any way to test these, to determine which one might be at fault? (Hoping it's the PSU that's having the problem, and not the mobo.)
2. Any other possible candidates for being the cause of the problem?
What do you think? Any suggestions that might lead to a solution are welcome!!!