What is causing my OC to sometimes revert to nonOC?

[Andvari]

I OC'ed my Q6600 to 3.0GHz a few days ago, and as far as I know it is running stable. I tried memtest for 2 full passes (took like an hour-ish) with no errors, ran Prime95 for an hour and a half with no errors/crashes, played Crysis, copied 50 or so gigs of files from my old PC to this one through my router... basically I've done all my daily Windows tasks, as well as a Prime and memtest. No errors or problems whatsoever.

Now most times when I reboot, everything is fine. But sometimes, it reboots, and after about 4 seconds, reboots again before my monitor even turns back on. When that happens, I check my BIOS and my OC settings have been reset to default. JUST the OC settings. I.e., the FSB, the RAM frequency, the voltages, and the PCIe frequency. My other BIOS settings remain as I've set them. Boot priorities, disabled Floppy Disk, enable USB keyboard in DOS, etc.

In most OC guides, I read that I should run memtest and Prime95 for 6+ hours each for a better stability assessment, but I haven't had time to do that yet. Running them each for over an hour, I thought was a pretty good indicator that I was good to go.

Any ideas what might be causing this?

 

[Thor86]

Originally posted by: Andvari
In most OC guides, I read that I should run memtest and Prime95 for 6+ hours each for a better stability assessment

You answered your own question.

 

[Andvari]

Oh, ok heh. I'll give those a shot tonight. I just thought if it was happening during a reboot only (and not even every reboot), that something else was amiss.

Case in point, what do I do if I run both of those for 6+ hours with no errors? Come back and post again? =)

 

[BlueAcolyte]

Yea...

 

[Phunk0ne]

it might be that your cpu is not getting enough volts to keep stable. Or maybe your ram is not getting enough volts to stay stable. I was getting this when I undervolted & underclocked my E6750 to 0.9V @ 1.6GHz. Everything ran like a charm, but when I would restart my computer, my Motherboard would reset the BIOS by itself and run stock @ 2.66GHz again. So I went back to my previous 3.8GHz overclock.

 

[Amaroque]

Originally posted by: Andvari
Oh, ok heh. I'll give those a shot tonight. I just thought if it was happening during a reboot only (and not even every reboot), that something else was amiss.

Case in point, what do I do if I run both of those for 6+ hours with no errors? Come back and post again? =)

Are you stressing all four cores with Prime95? Try the newest version that will load all cores here.

 

[Andvari]

Yeah I have the new version of Prime95 that stresses all four cores.

14 minutes into a Prime test, I got an error on the third thread. Strange I went error-less for an hour before. *shrug* Oh well, I bumped up the RAM another .1v. It says "+0.2v" now in the BIOS. I wish my BIOS would tell me what the actual voltage is now. If default was 1.8, then +.2 is obviously 2.0, but what if that's not what the default was?

CPU-Z says my RAM is 1.8v regardless of what I do in the BIOS.

 

[VirtualLarry]

CPU-Z doesn't display actual RAM voltage. You must be looking at the SPD screen, which is only the group of preset recommended settings.

 

[Andvari]

Yeah I was looking at the SPD tab.

Well I went 6 hours with no errors in Prime95 (Small FFTs; that's the test recommended in Graysky's sticky). When I head to bed in a bit, I'll set up memtest to run overnight.

 

[watek]

I just had this happen to me right now. Found my cause to be the CPUGTL option in the bios.