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7870 XT Overclocking issue

Discussion in 'Overclocking & Cooling' started by silkstone, Jun 26, 2013.

  1. silkstone

    silkstone

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    I recently bought a Powercolor 7870 Myst (Tahiti core) and i'm trying to overclock it.

    Does anyone know why the card flicks back to 925 mhz under stress testing (Furmark) no matter what the temperature is?

    I've tried using triXX and just CCC. The issue occurs in both cases. :confused:
  2. buildzoid

    buildzoid

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    It's probably because of the new boost system AMD has. So just use Unigine or the game Cube2:Sauerbraten as that catches instabilities in OCs without putting almost any load on a GPU. I know this works because it will throw artifacts earlier on the same clockspeeds as furmark and because it isn't synthetic the GPU will most likely run at max clock. The only issue is that if it artifacts once you have to restart the PC.
    silkstone says thanks.
  3. Jack1n

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    Did you set the power limit to +20%?
  4. james888

    james888

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    I have two of these cards. One can get to 1200, the other can get only to 1175. I say this just for example that I have not had these problems.
    Crunching for Team TPU
  5. Grnfinger

    Grnfinger New Member

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    I have the Sapphire XT's

    One will do 1200 and the other about 1175 as well.
    Cards load up with Heaven and 3D11 and do not change clock speed
  6. silkstone

    silkstone

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    I haven't adjusted the power settings and am measuring the clock speed in GPU-Z.

    I noticed it when I went for 1250 Mhz, the card didn't crash, but clocked itself down. Then, it started doing it at 1200 Mhz.

    Edit - Here's a SS. You can see it flicking to 1200 at the start but then flicking back to 925. The same happens with the memory clock; it is set to 1550 in triXX

    [​IMG]

    Edit 2 - I'm testing in Heaven at the moment and the problem doesn't occur until after a few minutes at 1250.

    Edit 3 - I seems to happen at all clock speeds, albeit after a longer interval, the lower the clock. The temps seem fine, maxing out at 68 C
    Last edited: Jun 26, 2013
  7. Jack1n

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    I would take a closer look at VRM temps..
  8. silkstone

    silkstone

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    How? :confused:
  9. Jack1n

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    Hmmm no Vrm sensor....
    make sure you power limit is +20% in trixx because some had a similar problem to yours and its what fixed it.
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  10. silkstone

    silkstone

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    I don'tsee a percentage in triXX, just an absolute value. Should that be slid to the max?

    Edit - It didn't help. It still flicks back after a few secs on Furmark.
  11. AlienIsGOD

    AlienIsGOD

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    weird that GPU Z has no VRM reading for your XT, my 7870 standard has VRM1 at the bottom of the sensors page wonder why the 7870 XT doesnt...
    silkstone says thanks.
    Crunching for Team TPU
  12. silkstone

    silkstone

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    oops. Just found it. You have to scroll down!

    VRMs are at 60 C when it flicks back to 925. They max just close to 80.

    [​IMG]

    the 12v goes down to 11.7 V, then back to around 11.8 V on that image from the standard 12.1 V when not at load.
  13. silkstone

    silkstone

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    Update - When I set the power boost to 20% in CCC, I no longer get the issue.
    I also manually have to set the fan to 100% in CCC otherwise it says at 50% :(
    Is it safe to run it with this boost?

    Edit - It seems overclocking in CCC and using triXX manual fan profile works ok.
    The VRMs reach 110 C tho!!!

    Edit 2 - That 110C temp is in Furmark. In Heaven, they stay at around 70 C. I think I might delete Furmark, I only hope I haven't damaged my new card.
    Last edited: Jun 26, 2013
    AlienIsGOD says thanks.
  14. AlwaysHope

    AlwaysHope New Member

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    I have 2 sapphire 7870s and have never touched the power control setting when overclocking. My question is does this influence GPU clock or Memory clock or both? :) Thx
  15. erocker

    erocker Super Moderator Staff Member

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    GPU clock. If the card goes over its power threshold, it will throttle. The memory is using its own set of vrms and voltage.
  16. AlwaysHope

    AlwaysHope New Member

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    Ok, thanks, I'll do some more testing tonight with that control but both my cards are factory overclocked anyway so I probably don't have much room left..

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