Overclocked CPU under clocks when reaching 50C

[ShattaAD]

Hey guys, I need some help here with figuring out whats going wrong. Though I'm relatively new to overclocking, I've OC a couple cpu(s) before(recently) but this is the first time I've decided to use Prime95 to stress test my cpu. The setup is as follows:

Processor> AMD Phenom II x6 1100T - O.C. to 4.02 GHz @ x20 multiplier [only] (Turbo Core/C1E/Cool n' Quiet all disabled)

Motherboard> ASUS M4A88TD-M (AI Tweeker BIOS Suite)

Cooler> Corsair H80 liquid-cooler

PSU> Corsair GS700

GPU> EVGA GTX 460(1024 MB)

HDD> Momentus XT + RAID 0(x2)

 

Issue: I'm monitoring using both SpeedFan and CPU-Z, both latest version. CPU-Z shows that I'm running at ~4018 MHz(after O.C.) @ x20 Multip. Soon after starting up Prime95(latest version) and running a stress test using multiple mode including Small FFTs, the CPU-Z reading goes from the expected 4018 MHz about 10 seconds in, to ~1706 MHz @ x8.5 Multip. at about the same time the CPU temperature hit ~51 deg C. After a minute or so running at 1707 MHz, it would jump back to 4018 MHz until the temp. hit ~50 deg C again where it would clock down to 1707 MHz. It does that in every test and in some attempts, it would stay indefinitely @ 1707 MHz after the first drop, for the remainder of the test. Whenever I stop the test, the CPU-Z reading goes back up to 4018 MHz. Should I trust the CPU-Z reading? Assuming that these values are correct, why does my CPU underclock itself like that even though I have C1E, Turbo Core & Cool n' Quiet disabled? Should I naturally assume that this has something to do with the temperature since it never goes above 51 deg C(temp. would go down after it underclocks)? I'm pretty sure the H80 can handle CPU temp. well in the 70 deg C range. If it keeps underclocking like that there's no way I could truely stress test my cpu and find out if this clock setting works with stability. Plz guys, any insight, explanation, diagnosis, anything would help ease my mind.

Thanks so much guys!

 

 

 

AD

[AceDeAce]

Are you sure all the power saving things turned off? Maybe reapply thermal paste?

[ShattaAD]

Are you sure all the power saving things turned off? Maybe reapply thermal paste?

 

I turned off Cool n' Quiet, TurboCore and C1E. These are all the power saving features that I know of, if you know any other plz do let me know.

I've already reapplied the paste, it made no difference.

Could software override the BIOS settings? I do have ASUS EPU running in performance mode though I'm not sure it does anything at all.

[AceDeAce]

Hmm... Is anyone else having this? Have you seen any other mention of it on google or something? It sounds very odd.

 

Maybe try and disable EPU, I have no experience with it but it might be the cause?

[ShattaAD]

That's the thing, I couldn't find much online with similar issues. Almost every piece I read on OCing Phenom 1100T suggest that the safe thermal envelope should be around 48-65 degrees C when overclocked to 4+ GHz and using a H80 cooler. This suggest that my CPU should be able to go above 50 C but it always clock down to 1.7 GHz when the temp. hit 50 C and why 1.7 GHz I don't get it? Why not 2 GHz or 3.3 GHz(original clock)?

[Drdeath]

C6

[ShattaAD]

I just use Phenommsrtweek to set all my P-state to x20 multiplier and CPU VID to 1.400. When I run Prime95, CPU no longer clocksdown and it stayed at 4.0 GHz. This is the good news...Bad news, vcore voltage was relatively high @ 1.464~1.524, result is a blown capacitor on my motherboard, I just heard a loud POP! and some vaporizing gas next to my CPU which is what I thought initially got fried but after I realized Prime95 is still running full gallop without error, I thought it strange. All system still function as normal, no BSOD, no restarts, no sudden shutdowns. Now I'm wondering why exactly did that capacitor got blown and what it does and how I'm still sitting here typing this up and finally, will it affects me in the long run, I've included a pic of the capacitor that had blown completely off(circled in yellow) which appears to have a 16V rating.

[Alexandre]

Doesn't sound good. It looks like it might be a CPU power regulation capacitor. I wouldn't risk using the board as it might be allowing badly regulated voltages to your CPU which will cause damage. Sorry to be a bearer of bad news but it might be time for a new MOBO

Edited December 12, 2011 by Alexandre

[d6bmg]

Looks like a problem with your board, most probably voltage distribution problem. You should send the board for RMA and shouldn't use it any more in the present condition.