PC switches off. overheating? faulty PSU? something else? help!

[jordan427]

* Motherboard: P5K SE/EPU - BIOS 0404
* CPU: Intel E6400
* RAM: 3gb Corsair XMS2 (512x2 and 1GBx2 - Matching pairs)
* Enermax 485W PSU






Hello all,

I've got this rather annoying problem which has cropped up recently. My PC will shutdown (as if I've just pulled the plug out) then it will switch on again and boot up. The times it does it are completely random, sometimes it will do it while windows is loading up, sometimes while windows has been running for a few mins, sometimes while it's on the POST screens. Sometimes it will do it 10 times in 1hr, sometimes it can be running 24hrs+ with no problem! My initial thoughts were overheating or faulty power supply, PC probe is telling me 30c for my CPU rising to ~40c under load. Also the voltages are ok (according to PC probe, I know these things are never accurate): 3.23v, 5.11v, 11.98v; Vcore: Fluctuating between 1.1v and 1.15v.

So far I've:

Cleaned out all the fans (they weren't even very dusty).
Reseated all hardware, basically rebuilt the PC incase it was shorting out or loose cable.
Tried 1 stick, 2 sticks, and all 4 sticks of RAM.


I'm really really running out of ideas. Any suggestions?

Thanks in advance

[kalniel]

Do you have a graphics card in there as well?

Are there any windows error messages in the event log?

Are you overclocking anything?

Have you done a full virus/malware check?

[jordan427]

Sorry, yes my graphics card is a GeForce 7900GS, everything is at stock speeds, and I'm running a virus scan now with AVG and there's nothing in the event viewer

[kalniel]

Other things to try:
-full memtest86+ check on the ram
-orthos stress test
-make sure the hard drives are running in IDE mode (not ACHI)
-replace CMOS battery

Otherwise I think you've probably covered the main things like shorting motherboard/EMI shield.

[Blitzen]

Sounds most likely an overheat to me.

Are you sure you fan on the HS is working?

[jordan427]

Yep, all fans working and cpu temps in bios and pcprobe read 30c.

[smargh]

No exposed shorts inside the PC? (i.e. dangling 3pin fan extension cables)

If it's plugged in to a power socket extension cable, try either a different extension or directly into the mains master socket.

You could do with getting a normal multimeter and checking your voltages that way rather than relying on the in-built PC stuff.

[jordan427]

Thanks for the help all. I don't believe there is any shorting problem after reseating everything, I could try using a different plug socket and getting hold of a new power cable. It hasn't shutdown since 6pm last night (it's now 13:30) but I don't believe for one minute the problem has gone.

[jordan427]

I've had another look in the event viewer and found a couple of entries around the time of my shutdowns last night.

'The COM+ Event System detected a bad return code during its internal processing. HRESULT was 8007043C from line 44 of d:\qxp_slp\com\com1x\src\events\tier1\eventsystemobj.cpp. Please contact Microsoft Product Support Services to report this error.'

Googled it and it seems it does cause shutdowns, but could it still cause shut downs during POST/BIOS? It's just a stab in a dark...

[kalniel]

No, software itself can't cause shutdown until it's loaded. But it more strongly points towards a memory problem. How long did you run memtest86+ for?

[jordan427]

I haven't, yet. Just about to burn it into CD then try it. How long should I leave it running for?

[alchemist118]

I suggest about 6 hours

[jordan427]

An overnight job then

[jordan427]

Ok, I ram memtest86+ for 9hours during the night and there was 2 errors. If I was reading it correctly it was at 2565mb, which would suggest one of the 512mb sticks was bad? (I have the 1gb sticks in slots 1&3) Or does it not work like that?

[jordan427]

Still having this ####### problem. I've taken the components out of their case and they're on a few books and it's still shutting down then rebooting. It's not a grounding issue, that's for sure.

I tried it with just the essentials. PSU, RAM, graphics card, CPU, still shutdown.

I've five sticks of ram in total: 2x1gb, 2x512mb, 1x512. I've tried all five. It's not a RAM problem, I'm quite sure.

Can't see this being a CPU issue, they rarely fail and when they do they usually fail big time.

So that leaves motherboard and PSU. Right now I'd say it was 50/50.

I'm totally sick to death of this problem, I have a faulty Gigabyte board which I am RMAing on 5th Jan so once a replacement arrives I guess it will narrow things down a bit.
*sigh*