PC goes on... off... on...

[flobear]

Hello everyone,

I built this computer myself and it's been working fine for about a year. Two days ago the PC wouldn't boot when I turned it on. Instead, it powered on for a few seconds, and then powered off, then on again and off and so on.

Troubleshooting So Far:
Power supply - I tested all of the voltages that come off the power supply with a multimeter (as per this guide here: PSU Test - How to Manually Test a Power Supply With a Multimeter - Test PSU)

Everything was within tolerances.

If I plug in the 24-pin connector (and only the 24-pin connector) to the PC, it powers on and stays on. I presume this means that the power button on the front of my PC is ok too.

I next plugged in the 4-pin motherboard power cable and the auto-power cycling problem resumes. Just to make sure the power button wasn't the problem, I disconnected both the power and reset buttons from the motherboard and powered on by shorting the connector pins. Same problem.

Any ideas?

Thanks in advance - great forum.

[stroyal]

Welcome to TechIMO!

I would check the memory.
Just to start/
Memtest86 - Download Page


Edit:
Probably not memory,
I would set it up with minimum setup and a different power supply, if it still does it, I would suspect the motherboard.

[flobear]

stroyal,

Thank you for your suggestions. I pulled the memory off the board and still experienced the same problem with the powering on and off. So I agree it's probably not the memory.

Your suggestion to use a different power supply is a great idea. I'll give that a shot today and we'll see if it works. I think I might have one somewhere in the basement :-)