Overclock guru stumped w/Prime? Please help.

[hotstocks]

I have been overclocking for 20 years and this one really stumps me. I recently changed my motherboard and cpu from an overclocked q9550 at 3.8ghz to an Asus P8p67 mobo with i2500k at 4.7ghz. My computer is completely intel burn test stable and prime stable at 1.27v (except at night, let me explain). If I prime during the day, while I am web browsing, playing games, etc. no problems ever, though I never used it more than 5 hrs. When I go to sleep I set up prime to run for 8-9 hrs and every morning my computer is turned completely off. So I bumped to 1.28v two nights ago, and then 1.29v last night and same thing. My instincts told me it would be the PSU, but it is a new Antec 650 with a UPS battery backup and it never uses more than 400 watts and any minor power fluctuaction is taken care of by the UPS backup. It actually uses LESS power because the overclocked q9550 was at 1.4v and I also removed a floppy drive and bay controller. But I did put in a Corsair H50 instead of a TRUE cooler (which uses a little more power). The rest of the system is geforce 580, Corsair Vengeance 8GB, creative Fatality sound xfi, and a few case fans. Also to note is the i2500k does 4700mhz at 1.27v and very cool (intel burn test 60's on realtemp), but no matter what I do, won't be stable at 4800mhz, and I won't go over 1.3625v to try. Thinking it was the psu (I have a dual monitor setup), I put prime running on high priority on one monitor and played Need for Speed Hot pursuit on the other monitor to totally stress out the CPU, Geforce 580, and PSU. Guess what, this killer system had me playing for hours at a pegged 60fps while priming! What a chip! So it is NOT the PSU, ram passes memtest and windows memory diagnostics. So I am baffled. Do you think this is some weird prime only teething problem with the Asus P8p67 pro motherboard? Some bios setting wrong? I am running the memory at 1T? Or something with the Corsair H50 after 8 hours of prime? Also all my voltage readings are perfect, slightly above spec on 12v, 5v, and 3.3v lines. Any help would be appreciated, I am completely baffled. It's a great system, maybe I should just not worry about prime turning my computer off after many hours? I would just be happier to see an error in prime or even a frozen or blue screen in the morning!

 

[rustEswan]

Its likely the memory controller falling over with the voltage that low. With intel burn test you're not stressing the controller at all. I know you say mem test runs ok but i doubt that is stressing all cores and the controller in one go. It'll probably burn test all day(and night) long but under prime blend you thrash the mem controller plus all cores and theres not enough vcore to cope.

Also are you sure you're mem is rated 1T at the specified frequency? And dont forget most of the bioses are flaky as hell at present, i've had issues with the SPD detecting auto timings wrong, auto voltages all over the place and vcore readings completely out in bios and cpu-z (unless you're on 1.56.2).

Also worth a note is the apparent multiplier wall people seem to hit - mine was 47, with latest bioses its 50. For example I couldnt hit 5.1ghz (51x100) but could hit 5.2ghz(50x104) at the same vcore.

It will take a while to get used to this architecture its behaves VERY differently to anything I've clocked before.

 

[spleenharvester]

Do you have any sort of batch scripts on it you could've forgotten about? Same thing happened to me, then I realised I made one to shut it down at 5am as an emergency backup.

 

[Scougar]

Or power settings/hibernate. I.e. if it's 'inactive' for that amount of time you may have set it to shut down?

Can you set Prime to 'log' what happens over night so you can check the output in the morning?

 

[1Day]

I suspect it has to do with the internal memory controller of the CPU and the intrinsic bios sub timings - similar problems have been noted by other Asus users.