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AMD FX8150 voltage drops under load

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November 11, 2012 7:29:23 PM




Can someone tell me why my CPU vCore fluctuates between the two values shown above?

Cool n' Quiet is off, and so is turbo core technology.



AMD FX8150
ASUS M5A88-m
8GB GSKILL DDR3 1333, 9-9-9-24
a c 109 à CPUs
November 11, 2012 7:33:34 PM

Can you tell me which one is which? Since Prime95 in the background is nearly identical, I can't tell which is idle and which is load. Perhaps a screenshot with Task Manager would be good :) 
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November 11, 2012 7:40:05 PM

Prime 95 was running for both pics, the voltage swaps back and forth every few seconds along with my multiplier. When on idle the voltage stays high consistently.

and here's a view with task manager open
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a c 109 à CPUs
November 11, 2012 7:41:57 PM

Thank you for clarifying that.

Can you tell me your CPU temperature? I'm now concerned about thermal throttling.
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November 11, 2012 7:50:56 PM

The CPU temp gets to approximately 55*C and then drops below 50 once the voltage drops. I have Corsair H40 liquid cooler and 55 degrees doesn't seem that high to me?
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a c 109 à CPUs
November 11, 2012 8:27:42 PM

No, that's not high at all. I had a forum thread with an issue VERY similar to yours...Trying to see if I can find it since I think it'll be of help.
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November 11, 2012 8:33:47 PM

Thanks mocchan i hope you can find that thread because this problem has been bugging me since day one with this setup.
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November 11, 2012 11:06:12 PM

So after further examination the voltage seems to drop when the CPU socket reaches anything above 50*C. Is there a setting that I can disable in the BIOS to stop this thermal throttling?
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a c 109 à CPUs
November 11, 2012 11:10:56 PM

(I'm still looking for the link, by the way)

There should be a setting inside BIOS that lets you disable this from occurring. What is the exact model of your motherboard?
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November 11, 2012 11:15:27 PM

The exact model is ASUS M5A88-m, and I've looked all through the BIOS and I can't seem to find such a setting?
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November 12, 2012 2:57:26 AM

Is it possible that it's the actual motherboard that's throttling the CPU because the board is getting too hot? Maybe the VRMs?
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a c 109 à CPUs
November 12, 2012 3:01:58 AM

That's always a possibility but I would highly doubt it as your motherboard should be able to support 125w TDP CPU's without any issues. As long as you're running at stock frequencies you should be fine :) 

I just dug through my motherboards to get my brother's old GA970A-D3, I couldn't find anything about thermal throttling as well, unfortunately.
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November 12, 2012 3:23:15 AM

Well thanks for your help, I put new thermal paste on a heat sink on the chip that is just beside the CPU slot, seems to have helped a bit but even at stock speeds, while under Prime 95 stress test it reverts back to 7x multiplier and low voltage... I found a few other posts on google by people having the exact same problem as me with the same mobo/cpu combo. I'm beginning to think I might need to invest in a better board. :( 
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November 13, 2012 1:03:22 AM

Hey mocchan did you end up finding that forum?
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a c 109 à CPUs
November 13, 2012 6:26:15 AM

masterelyt said:
Well thanks for your help, I put new thermal paste on a heat sink on the chip that is just beside the CPU slot, seems to have helped a bit but even at stock speeds, while under Prime 95 stress test it reverts back to 7x multiplier and low voltage... I found a few other posts on google by people having the exact same problem as me with the same mobo/cpu combo. I'm beginning to think I might need to invest in a better board. :( 


Yes, investing in a better board may be the best option. Though, I'm a bit curious, you're running at 4Ghz when stock FX-8150 speeds are 3.6Ghz (unless TurboCORE frequency is 4Ghz...Can't remember).

Unfortunately, no, I couldn't find that forum thread :(  I've been search the entire day today through my bookmarks and searching for keywords on Google, but no luck.
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November 14, 2012 2:15:01 AM

At the time of the pictures I had the CPU running with a slight overclock by changing the multiplier to x20. The throttling happens at stock settings too, only it takes longer than when running at 4Ghz.

Also, I really appreciate the effort you've put in trying to help me. I've been exchanging emails with ASUS tech support since last night and I'm awaiting a reply, maybe I can RMA the board or processor? The way I see it this processor is listed as fully compatible with the motherboard so it shouldn't have any issues at all!
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a c 109 à CPUs
November 14, 2012 4:00:07 AM

Yes, the CPU should be 100% supported without any hassle; it may be a board problem at this point. Considering you're not doing any overclocking, and since the board should be able to accept 125w TDP CPU's without a hitch, I can't think of any reason why this is occurring..unless I've been blind and I'm missing something obvious.

The CPU shouldn't need an RMA, they RARELY have problems :)  It's more likely a board issue at this point...
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November 17, 2012 12:59:33 PM

Make sure you disable Cool n' Quiet in the BIOSi; this will throttle down the CPU. There were some other states I had to disable, can't remember them off the top of my head. Once you do that, you should be staying steady.

You also mentioned running at 50C with water. That's also perfectly normal under load. For this chip, 61 is where you want to start getting concerned.
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November 26, 2012 2:37:39 AM

I know this thread is kind of old but I threw the stock heat sink on to see if maybe the cooler is an issue. Temps get a lot higher than before, up to 64 (that's when I shut the test down) but no throttling whatsoever. Not sure why but I might buy another cooler, as that seems to be the issue here...
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November 27, 2012 1:43:28 AM

I believe I've figured out what was causing the problem. Something on the board (mosfets or chipset) were overheating. Pointed a big fan right at them and now there is no throttling whatsoever! Evidently this board isn't the best and I will replace it eventually but this solution works for now. Thanks everyone for your help :) 
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November 27, 2012 11:07:42 PM

Went a little further regarding cooling these VRMs, I bought little heatsinks from a shop in town and cut them to size. They stick on with some sort of adhesive. These heatsinks coupled with the airflow from the new fan mean that these VRMs stay nice and cool now, I guess when the board was tested by ASUS they used the stock air cooler, had they used the water cooling they would have experienced the same issues I did. Here is a picture of the heat sinks if anyone is interested:



Oh and the heatsinks match the colour scheme of my motherboard, bonus. :) 
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November 16, 2013 3:40:16 AM

I have invested some cache in Thermalright HR-09U type 2 and with stock cooler it keeps downclocking but much longer to wait...
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