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CPU underclocks to 800 Mhz when stressed?

Discussion in 'General Hardware' started by ObsoEU, Mar 14, 2013.

  1. ObsoEU New Member

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    I recently bought myself a new CPU (phenom II X4 965 BE) and when playing games it likes to under clock itself to 800 MHz randomly for a few seconds which causes me to get 5fps for a while. I've searched quite a lot about possible causes to this and I've followed a few solutions to no avail. These "solutions" were to disabled all motherboard cpu features, disable AMD cool and quiet and update my motherboard BIOS. Also to change the windows power settings to high performance. I have tried all of these methods and this is still happening to me. I have nowhere else to turn. Does anyone have any idea why this might be happening?
     
  2. RCoon

    RCoon Gaming Moderator Staff Member

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    The Asus M4N68T-M LE V2 has full 95W processor support, and claims to support 125W processors (your Phenom 965 is a 125W processor), but simply isnt pushing enough power to the CPU. Disabling cool and quiet was my initial thought, but if you have already done that then i doubt that is the issue.
    Please note that TDP is not power usage, but there generally is a correlation between heat produced (TDP) and power needs.
    Your CPU is throttling itself because it's not getting enough juice from your MoBo
    EDIT: The VRM's will also throttle the CPU if they get too hot, they're not rated for much stress.
     
    Last edited: Mar 14, 2013
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  3. TRWOV

    TRWOV

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    In my experience, Phenom II (and other AMD CPUs) will go into "safe mode" which clocks down the HT link to 1000 as well as the north bridge and the cpu down to 800mhz. So, yeah, your motheboard VRMs can't provide enough power for the CPU to keep it at its rated speed. If you disable a core and down-clock a bit you might get better results.
     
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  4. RCoon

    RCoon Gaming Moderator Staff Member

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    He said it only seems to happen in games for a few seconds when under particular stress, leading me to believe it's booting fine (when not under load) and not in safe mode.
    If you look up his MoBo specs, it doesnt even have any heatsinks on the VRM's.
     
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  5. ObsoEU New Member

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    It does boot fine. I thought I would not need to worry about support for the 125 TDP processor as you said, my motherboard claims to support 125. So I should try under volting/clocking of my processor and look into getting a replacement motherboard then? Thanks so much for your help.
     
  6. red_stapler

    red_stapler

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    I'd suggest undervolting first. The 965 seems like it can go down pretty far in voltage before it becomes unstable. I think i was running mine at something like 1.275v at stock clocks to keep it cool,(i was using the heatsink from a 95w triple core) and it ran games fine.
     
  7. TRWOV

    TRWOV

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    Many 95W motherboards will claim to support 125W CPUs but the term support just means "it will boot". I have an ECS 780G board that "supports" 125W CPUs in safe mode, I'd guess that your board is similar. Undervolting would help.
     
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  8. ShiBDiB

    ShiBDiB

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    If it didnt get power it would BSOD not downclock.. this sounds like a heat problem
     
  9. ruff0r

    ruff0r

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    As he says Maybe they are running hot try to place a fan above the VRM directly and test again if it only are the temps keeping it down by buying some cheap heat sinks to put on and run them cooler
     
  10. terrastrife New Member

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    multiplier downclocking is pretty darn common. AMD keep changing their CPU VRM input design each core that motherboards keep needing to be revised. ie, Bulldozer works perfectly fine on my motherboard, but Piledriver doesn't.

    my FX downclocks to 17x (on 2 or 4 cores) due to the motherboard not being able to provide clean enough stable power to the CPU. Even still, I have a overclocked Turbo frequency because parking the idle cores keeps the CPU well down on power usage. Only happens with stress testing 8 threads. Games spend most of their time in full Turbo. No amount of undervolting saved me.

    But my X6 drawing 250W+ was no problems.
     
  11. xorbe

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    Check the paste between the cpu and heatsink? What are the temps ....
     

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