I built my first (and only) comp approx. 5 years ago - and for five years all has been great. Today, though, no so much. In moving my office around a bit, the comp was moved around the room a few times. Upon putting everything back together, the comp would not start. It would turn on (all fans) for about 10 seconds, then power off. (After being off for 3-5 seconds it would turn on by itself for 1, off for 5, on for 10... repeat the whole thing).
I opened the case to find the CPU / heatsink fan not firmly connected (not sure how it came loose...). I suppose trying to load with the issue could have fried it, but I'm praying not.
I reseated the CPU/heatsink - cleaned both with alcohol, reapplied thermal paste, reconnected. Same problem.
After searching this forum and many others I saw some people discuss issues with the power button on some cases. I opened the front of the case and peaked around, saw no issues. But now, after reconnecting the front of the case, I don't get any boot at all. When I push the power button, I get a flash of power and a spin of all fans, and then instantaneously off. [UPDATE - this problem has disappeared. Back to the original brief surges of power - 5-10 seconds - and then dying.]
I'm no pro on any of this - in fact, it was a minor miracle I put the thing together right 5 years ago and have never had an issue til now!
It sounds to me like a PSU issue - but I can't figure out what would have killed the PSU in the 30 minutes it was disconnected. Unfortunately, I don't have the money to buy both a new PSU/CPU/computer in general.
Any diagnosis thoughts?
Processor - Pentium E6300 (dual core 2.8ghz)
Power Supply - Rosewill RP550 - 550w
Motherboard - ASRock P45XE 775
RAM - GSKILL 4GB (2 x 2GB)
HD - Western Digital Caviar Blue WD3200AAJS 320GB 7200 RPM SATA 3.0Gb/s
Case - COOLER MASTER Elite 330 RC-330-KKN1-GP
Honestly, it does sounds exactly like what would happen if the power button was getting stuck in an "always on" position. It's likely nothing would be physically obvious just from looking at it, but it could still be sending a constant signal as if you're holding the button down. The way to check this is to disconnect the front panel buttons from the motherboard and try starting it by shorting the two "power" pins with a flathead screwdriver. (You should look up your motherboard's user manual; it will tell you which are the correct pins). Another way to do it would be to switch the connectors for the power and reset buttons so that you're essentially using your reset button as the power button, and see if the problem goes away there.
Another thing that can happen with old machines is that the battery on the motherboard goes dead. It's responsible for preserving your BIOS settings when there's no power to the machine. So when that battery dies, as long as your machine is still plugged into the wall, everything is fine, but when you unplug it to move it, then the BIOS gets wiped and resets back to factory defaults. I don't think this would normally cause the kind of problem you're having, but it is worth checking out while you're in there, given the age of the machine.