My computer turns on then off repeatedly until i unplug it

[Brianlt123]

Hey guys. This is actually happening to two of my computers. both with identical gigabyte motherboard and intel processor. The computer turns on then about 10 seconds later everything shuts down, fans turn off, then it comes back on within a second. connected to a monitor and I never have an option to go into bios.

Computer 1: it was working fine. I sold it on craigslist so i use the wipe feature on ccleaner to make sure my personal files couldnt be recovered.(not sure if that has anything to do with it) But it was working fine before I sold it. They got it home and it started doing the restart thing on them.

Specs:
Mother board: gigabyte s-series. GA-EP35C- DS3R
power supply = 450 watts
Video card = Geforce 9800 GTX 512mb
CPU = intel core 2 quad - Q6600 2.4 ghz
Memory = 3.5 gb (ddr2)
dvd drive
Hard drive: 300gb with windows xp installed

Computer 2: I got the other computer out from storage to help guide them through some trouble shooting (see what they see type of thing). The computer had been in storage because the power supply died on me. I decided to throw in another old power supply and turn it on. IT DID THE SAME THING (i've never encountered this problem) turns on then off repeatedly until i unplug from wall. I unplugged the hard drive, still does it. I unplug the video card, still does it, I only left 1 stick of memory in, still does it. I unplug the power to the CPU it stays running but bios never shows up.

Specs:The only difference is an AMD radeon 4870. and the power supply is 850 watts. But again its old.

 

[alexoiu]

Hi,
With computer 1: I can only guess that during transportation some component got damaged. What CPU cooler installed on it? Ask them also to re-seat the memory modules.
With 2, "The computer had been in storage because the power supply died on me" It might be more than a defective power supply (motherboard and / or CPU).

 

[Brianlt123]

This to me seems like such a rare malfunction and the fact that both of them are doing it is insane to me. I've had many computer issues over the past 12 years and there has never been one where it continuously turns on and off repeatedly. I'm going to put in a fresh power supply onto the second computer. But does anyone think that the CCleaner wipe feature could have messed up my hard drive in such a way that would cause my computer to continuously turn on and off?

 

[Brianlt123]

I put a new power supply in (750 watts) still keeps turning on and off. How do I test the motherboard and CPU?

 

[Brianlt123]

I reset the CMOS battery. left it out for 30 min and put it back in and it worked! that fixed computer 2, going to see if it works for my craigslist customer. FINGERS CROSSED!

 

[alexoiu]

Is it the same on and off when starting the board with only CPU and CPU fan installed (no RAMs or other components)?