1. Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

Windows messing with CPU Vcore?

Discussion in 'Overclocking & Cooling' started by Vinska, Sep 25, 2012.

  1. Vinska

    Vinska

    Joined:
    Jul 23, 2011
    Messages:
    1,375 (1.27/day)
    Thanks Received:
    1,180
    Location:
    Kaunas, Lithuania
    I was overclocking my Bulldozer and I hit a wall very quickly. No matter if I increased my Vcore over the default a little or a lot, it would fail the very same way.
    Then I noticed a strange thing:
    Whenever my CPU was under load the Vcore would drop, the more load on more cores it had, the more it would drop. With 2 Cores on full load drops by ~ 0.05 V; With 4 Cores - by 0.09 to 0.12 V (would start making occasional calculation errors); With all 8 cores on full load at once, I would see the Vcore to drop to <1.2 V almost in an instant. That is way below the voltage needed to run at such clock speeds so my computer would freeze in a second or two.

    I thought it my be my PSU at first. I could see the PSU was running on less than third it's maximum capacity, thus barely loaded. And that PSU is quite new. So unlikely a PSU problem.
    It seemed is as if something would try to enforce the TDP in any means available. And since I had all the power saving features turned off, it suspect it goes after my Vcore to to so.

    Now it get to the weird part:
    I was doing it on Windows. Almost solely because I wanted to use CPU-Z.
    Now, I went back to Linux, where I usually "live". I can see the clockspeed of my CPU there, but can't monitor the Vcore. I kept the same clocks and voltages. I then went on to stress my CPU there. I was surprised - it ran rock-solid with all of my cores on full load. As if the CPU would get the voltage I intended.But running rock solid on Linux with what would would crash Windows in mere seconds? That is really odd.

    I suspect it could be that Windows or it's chipset drivers are enforcing the TDP.
    I also suspect one other thing: I am using the latest BIOS. And a couple of BIOS versions back, the changelog says "Add VRM MOS protection". Maybe the BIOS is F***ing with me by enforcing that TDP? I suppose Windows honor what BIOS decides, while the Linux kernel is known to sometimes not give a f*** over what BIOS says when it wants / knows better and overriding it's functions (thus explaining not enforcing this presumed limit).

    Does that mean "Windows be bad for 'dem bulldozers & Piledrivers"? Since A BIOS update to support PD CPUs probably wont remove this.

    Expert advice on what to do in such situation would be great.
    Crunching for Team TPU
  2. Jstn7477

    Jstn7477

    Joined:
    Aug 30, 2009
    Messages:
    3,776 (2.13/day)
    Thanks Received:
    1,482
    Location:
    Sarasota, Florida, USA
    There are some settings in the BIOS/UEFI that appear to "cause massive vdroop" like symptoms from my experience with my ASRock 990FX Extreme4. Let me take a look real quick, but I bet one of them is called "APM."

    EDIT: Settings to try disabling and seeing which ones affect you (I'm not going to mess with mine as I don't have time to test):

    Core C6 state
    Enhanced Halt State (C1E)
    Cool 'n Quiet (not sure if that causes the throttling as well. All I know is that BD works a lot differently than Phenom).
    AMD Application Power Management
    Crunching for Team TPU More than 25k PPD
  3. Vinska

    Vinska

    Joined:
    Jul 23, 2011
    Messages:
    1,375 (1.27/day)
    Thanks Received:
    1,180
    Location:
    Kaunas, Lithuania
    Thanks for replying
    But as I wrote: I have all the power saving features off. In other words - all those are turned off.

    P.S. *sigh* I wish it was something as simple as that. If I could set something in my BIOS to fix this, I would have done it. Yet I am already out of things that mess with clocks/voltages to disable. I hit a wall at trying to solve this myself =|

    EDIT:
    P.P.S. As soon as I get my UPS up, I will try to downgrade my BIOS to see if the problem is in that update. But, if this shows that to be the case, I can't use this "solution" if I want to upgrade to Piledriver. :shadedshu

    P.P.P.S. @Jstn7477 Seriously! :p
    Crunching for Team TPU
  4. Jstn7477

    Jstn7477

    Joined:
    Aug 30, 2009
    Messages:
    3,776 (2.13/day)
    Thanks Received:
    1,482
    Location:
    Sarasota, Florida, USA
    Yeah, I was extremely irritated with my FX-8150 and overclocking for a while. I had to set 1.45v in the BIOS to do 4.2GHz and it was ridiculous because it looked like my board had horrific vdroop as it would go down to 1.32v! Once I disabled those settings, I now set 1.275v in the BIOS and the voltage doesn't even budge.

    One more thing, did you disable Turbo Core as well? I disable turbo boost/turbo core on every machine I own because I do distributed computing and the processor will just run all cores at the lowest frequency anyway. Turning off turbo for me assures me that one core won't go to 4 billion GHz and crash the system. :)
    Crunching for Team TPU More than 25k PPD
  5. Vinska

    Vinska

    Joined:
    Jul 23, 2011
    Messages:
    1,375 (1.27/day)
    Thanks Received:
    1,180
    Location:
    Kaunas, Lithuania
    Yes, I had [and still have] it disabled.
    No use in keeping it on - as it won't work when AMD APM is disabled anyways. For me, at least. ;)
    Crunching for Team TPU

Currently Active Users Viewing This Thread: 1 (0 members and 1 guest)

Share This Page