Motherboards Post-short issues

Hi,

Some forum members very kindly helped me out with a shorting issue a few weeks ago. I'd inadvertently left an extra stand-off in place. Once removed the issue seemed solved.

However... a couple of weeks later, the problem has now returned. The machine will power up for a few seconds, sometimes a few minutes and then simply power off.

This is now happening even with the motherboard isolated from the case on a piece of cardboard. The mobo power light is on and I have checked, checked and re-checked all the connections.

Any suggestions please? I don't know in what order to now check things in order to isolate the issue and avoid replacing everything.

Thanks

 

What sort of temperatures are you getting?

What's the PSU?

 

When it's worked ok, the temperatures are fine. I've checked the CPU cooler mounting and it's properly in place.

The PSU is an Antec Truepower 550W modular. New about 3 months ago.

 

Switch on the PC, go into the BIOS and go into the PC Health screen. See if the temperatures shoot up before it powers off.

If not, does it power off even when just sat idle, or only when under load?

Have you tried clearing the CMOS and loading some defaults?

Is anything overclocked?

What sort of voltages are you running? Is your RAM/CPU getting enough juice?

 

It won't power on for long enough to get into the BIOS, it is only on for a few seconds.

It will power off at any moment. It's not used for anything intensive, just surfing and documents.

No over-clocking. It's just a machine I put together for my other half to do her admin stuff and use the internet.

Asus P5Q Pro, E7400, 4 x 1GB 800 RAM. Single HDD, single optical. 8800GT GPU. Power supply should be more than enough.

 

Hmmmm... clear the CMOS with the little jumper or by removing the battery for a few seconds.

Failing that, try reseating the CPU cooler. You'll need to clean off the old thermal paste with isopropyl (rubbing) alcohol or white spirit then reapply some thermal paste.

 

Thanks for your help capnPedro.

Cleared the CMOS and it booted. Left it idling and it seemed ok. However, when I went back to it... maybe an hour later... it had auto-slept. It restored ok, but then a few seconds later rebooted itself.

I will try reseating the CPU cooler, but have to say this doesn't seem like an overheating issue.

 

If clearing the CMOS worked (at least for a while) I'd rule out overheating too.

It sounds more like a dodgy BIOS option somewhere - probably voltages. Although I might be expecting a BSoD rather than a hard lock.

Run memtest86+ to rule out RAM and RAM related option (in which case it's probably CPU related).

 

Check the power lead going into the PSU, if possible swap it for another 1, I had a similar problem where the pc would just reboot at random and it was as simple as swapping the lead over to sort it out. Got to worth a look.