Occasionally won’t boot

This has been going on for about a month, perhaps once a day or a couple times a week. Occasionally on pressing the power on button nothing happens for 5-8 seconds, then boots up normally and runs fine. Now a few times a week the power comes on and only the drive indicator and several lights on the MB light up with the drives and fans spinning. The first time it happened I removed every removable item from the MB, PCIs, memory, drives etc. nothing worked until I disconnected the 20 pin connector & re plugged it in, worked for about a week trouble free. I replaced the battery. It continued to happen a couple times a week and reseating the 20 plug got it going each time. Yesterday it happened soon after shutting down and trying to reboot. Getting to the 20 pin connector is a hassle so I tried just unplugging the 120v for a few minutes and low a behold it booted fine.
I am pursuing this as maybe it can be fixed before it’s totally dead at a very inopportune moment. TUIA for any pointers I’ve overlooked.confused

Solid 5 &12V out of a 525W Power Cooling PS, Abit IC7 MAX3 MB, about 3years old.
P4 2.8 CPU, 2- 1G Mushkin modules, NO over clocking, 1-3 drives at times hooked up, runs cool with about 6 fans and open sides.
TY AND BE WELL

 

Do you have a SATA hdd? I know my pc boots too quick sometimes and it'll just set on the mobo splash screen until I hit reset. I don't really know why it does it.

 

I have Sata and Pata, makes no differance as all was removed the first time.

 

It happened again late yesterday, I pulled the power cord for a couple minutes, then it worked fine. ANY IDEAS????

 

Maybe the power supply's crapping out. I don't really know that's weird.

 

It's a possability, though I put a good meter on the 12 volt line and that sucker stays a constant 12.12 and 5.16 volts out of a 525 watt PCPower and Cooling unit, a great unit but not saying it's not confused getting flaky after 4 years.confused

 

Did you take the processor out and clean round and reseat. ?
By clean round I mean clean off any deposits on the mobo capacitors, or between tracks.

Also clean out inside the psu, look for burnt areas inside if you are prepared to take its lid off, blow hard through it with an air line if you are not.

Also spray some switch cleaner spray on the switch and plug and unplug the motherboard end of the switch cable several times.


Studio T