970A-UD3 and FX-8120 won't run rated speeds (3.1GHz) at full load.

[MarkJohnson]

I just bought this motherboard after my ASRock board was doing the same thing (plus the ASRock board would throttle down to 1.4GHz at 53C, that this board doesn't)

It just won't run at 3.1GHz at full load (prime95).  It bounces between 2.8GHz and 3.0GHz.  I tried to manually set the clock speed and even raised in to 3.2GHz and it still doesn't want to go past 3.0GHz.

I've replaced this CPU twice with the same issue.  although I only tested the second one on the board.

I've tried disabling cool & quiet and c1/c6 and turbo boost.

Not sure what else to try.
-=Mark=-

[Arith]

I've got the same combination and are interested in the replies you get. I haven't had a chance to test mine yet, first I had to ensure the backup was ok and since I don't have a spare monitor, it will have to wait until I get a new one. I hate dismantling this pc.

I have never used prime 95, it uses something called fast Fourier Transform, which is a polynomial approximation and it is a very long time since I did any calculus, but these equations can be very big.

Are you sure it is the cpu, and not a bottleneck or something.

[MarkJohnson]

I finally got it to stay at full speed on full load, but only with wPrime and HyperPi.  Both Prime95 and Intel Burn Test make the CPU throttle down to 2.8GHz.  I even manged to finally get this board to over clock after raising the "CPU Frequency" to 205MHz otherwise my clock speed would revert to stock speed (200 x 15.5).  Even at 4.3GHz it still drops to 2.8GHz.  I thought it would at least scale, but no.

Any clues why Prime95 or IBT won't run at rated speeds?

Any other stress test to try?
-=Mark=-

[Arith]

Same on mine 

[ifed32]

Turn off APM in Bios. That should fix it. Also you will need one one of the lastest BIOS's

[MarkJohnson]

Well, I just installed the F5 BIOS and things aren't any better.

I can't seem to keep this thing from throttling the CPU.  Even at stock settings it throttles badly.

anyone have any clues what's going on? 

I'm open to any suggestions. 

-=Mark=-

[MarkJohnson]

OK, I installed HWMonitor and I notice it throttles down when tmpin2 reaches 42c.  I thought I read that was the mosfets, but I thought they were suppose to be rated to near or above 100c?

I tried placing my 120mmx38mm  San Ace with 110CFM+ and temps didn't change at all.

what is tmpin2?  I've placed the fan in various locations with no effect whatsoever on tmpin2.

-=Mark=-

[MarkJohnson]

Turn off APM in Bios. That should fix it. Also you will need one one of the lastest BIOS's

That worked this time.  I got F5 BIOS and now it seems to work correctly.  I've had tmpin2 up to 58C @ 4.4GHz with no throttling.  If I re-enable APM in the BIOS, it throttles back down to 2.8GHz as soon as it hits 42C-44C.

Thanks for the help
-=Mark=-

[omagic]

Tmpin2 seems to be CPU temperature(not the single core temp)
To make sure You can check it with the Easy Tune and hwmonitor if CPU temp = tmpin2

[MarkJohnson]

Tmpin2 seems to be CPU temperature(not the single core temp)

Yes, you are right.  tmpin0 = et6 System temp.  tmpin2 = CPU temp.

not sure what's the difference,  how to cool it better, where exactly it's located, or why it is set so low (42C).

To make sure You can check it with the Easy Tune and hwmonitor if CPU temp = tmpin2

Reluctantly, I installed ET6.  but it showed me what things are in HWMonitor.

-=Mark=-