ATi HD2600XT Severely Underclocked

Discussion in 'Mac Pro' started by Mercuric Oxide, Feb 16, 2008.

  1. Mercuric Oxide macrumors 6502

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    #1
    I checked the core and memory clock speeds of the 2600 and was shocked at what Apple had done.

    The stock 2600 speeds should be:

    Core Clock: 800 MHz
    Memory Clock: 1.1 GHz

    Apple's Take:

    Core Clock: 695.25 MHz (down 15%)
    Memory Clock: 792 MHz(down 39%)

    I used AMD's GPU Clock Tool to *safely* raise the speeds.

    I set Core to 769.50 and Memory to 990. Any higher and your card will sometimes crash, so i recommend those, should you try this (at your own risk).

    Can anyone use a similar tool to check the 8800GT speeds?
    The Core should be around 625 MHz, and Memory 1.8 GHz
     
  2. Brianna macrumors regular

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  3. fs454 macrumors 65816

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  4. Mercuric Oxide thread starter macrumors 6502

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    #4
    http://www.nvidia.com/object/ntune_5.05.54.00.html

    That program will tell you the clock speeds of the 8800 (this is done in windows if I wasn't clear..)

    You can also raise the clock speed, although I'd only raise it to just below what the original clock speeds should be at most, since I'm not sure what other modifications Apple may have made to the card. If you raise it too high, your screen will turn black for a second then return, with the speeds set back to default. So if that happens, you know you went too high.
     
  5. Mercuric Oxide thread starter macrumors 6502

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    #5
    You raise the speeds in Windows, but this changes the setting of the physical card, so the benefit is evident in both Windows and OSX.

    Although, I'm not sure how Mac's handle overclocking, so do so at your own risk, and only overclock to what the original speed should have been. This should be safe as the card is already underclocked, and can be safely risen past the original clock.
     
  6. Mercuric Oxide thread starter macrumors 6502

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    #6
    Also, raising the speeds like I did (Core to 769.50 and Memory to 990) only made the ATi run +1.8 C higher on average, so those speeds are pretty safe and still underclocked from the original speed.
     
  7. Brianna macrumors regular

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    #7
    It's going to take me a few days before I can do it then. I just bought windows XP Pro SP2, and it wont arrive until thursday or so. Monday is a no mail holiday. Thanks for the utility though. I have a feeling that someone else will beat me to it, but I'll still do it and contribute my results. :)
     
  8. Sun Baked macrumors G5

    Sun Baked

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    #8
    Apple downclocked it to meet their power requirements for 4 slot operation.

    Raising it in the slots that can handle it should be too big a problem -- though those words usually melt silicon.
     
  9. Cuyahoga macrumors member

    Cuyahoga

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    #9
    What kind of benefits have you noticed with those settings?
     
  10. Mercuric Oxide thread starter macrumors 6502

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    #10
    Games get a 10-15% fps increase
    Some hi def video formats (.mkv, etc) that used to stutter somewhat in full screen no longer stutter
    Increased performance in 3-D apps like Maya.

    The 2600 is a midrange card, so OC'ing doesn't yield any spectacular gains in particular, but I prefer that my card run at the speed it's supposed to.

    Apple already stuck an EOL, low power card in the base MP, I don't see any reason to underclock it.
     
  11. Mercuric Oxide thread starter macrumors 6502

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    #11
    Anyway, just remember that there's a small chance you may mess up your GPU or reduce its life (very small as it's underclocked though)

    I only OC'ed mine because I'm getting the 8800 in a few weeks, so it will no longer be used. I don't plan to mess with the 8800 (although if it's severely underclocked like the 2600..)
     
  12. Wild-Bill macrumors 68030

    Wild-Bill

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    #12
    Can they legally call it a 2600xt then??? Apple underclocked it to Pro speeds. Any legal eagles out there wanna chime in about this? I am of the opinion they shouldn't be calling it a 2600xt if it does not perform at 2600xt speeds.

    This has me curious. I wonder what my "8800GT" is actually clocked at...
     
  13. netkas macrumors 65816

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    #13
    In opengl drivers, it called 2600 Pro, in System profiler it called just 2600.
     
  14. JonR356 macrumors member

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    #14
    I used the auto overclocking function in the ATI drivers. It increased the clock and memory speeds, though not quite to the extent recommended by the OP
     
  15. macz1 macrumors 6502

    macz1

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    #15
    Is there a way to see / modify the clock speed of the graphics card in OS X? Aticcelerator II works only for older cards
     
  16. dukeblue91 macrumors 65816

    dukeblue91

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  17. mmccaskill macrumors 6502

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    #17
    Then why underclock it and call it XT? Just put in a PRO and leave the clock settings.
     
  18. rtrt, Feb 17, 2008
    Last edited: Aug 13, 2011

    rtrt macrumors 6502a

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  19. Brianna macrumors regular

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    #19
    How is it that you are certain that Apple did anything to these cards? ATI, as opposed to Nvidia, makes their own graphics cards, and supplies Apple with drivers. Where as Nvidia on the other hand does not manufacture a video card for Apple or write Apples drivers. How do you know ATI did not send your particular card to Apple that way? Do you have a memo? ;)
     
  20. barefeats macrumors 65816

    barefeats

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    #20
    ATIccelerator II (and Graphiccelerator) are utilities that run under Mac OS X. I used to use them to sample core and memory clock speeds of ATI cards and sometimes overclock them by 10%.

    I don't know if they have been upgraded lately to work with the new Mac Pro but you might contact Thomas Perrier, the author, to check on the status:
    http://thomas.perrier.name/graphiccelerator.html
     
  21. barefeats macrumors 65816

    barefeats

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    #21
    I used Graphiccelator under Mac OS X to a "confirm"* that the Radeon HD 2600 XT is running at 695MHz core and 792MHz mem.

    (*It has an ATI frequency check. It was off by a tenth -- 69.5 and 79.2 -- but I consider it confirmation.)

    Now I'm curious about the GeForce 8800 GT, too.
     
  22. Kuraudo macrumors member

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    Feb 19, 2007
    #22
    What a **** deal. Its already slower than x1900XT and then Apple had to cripple it again. The X1900xt comes crippled at 1296mhz from when I used it.
     
  23. Brianna macrumors regular

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    #23
    I emailed the author of those apps and asked if he would join our discussion. I want to know the answer too. I have an 8800GT. I think in one of those apps you could copy a ROM from an older series of Nvidia cards besides changing it's settings. I'd like to flash a Gainward BLISS 8800 GT 1GB Golden Sample with the Apple ROM. Or maybe an EVGA e-GeForce 8800 GTX or GTS ACS3, or something else I turn up in a search that screams.
     
  24. Eidorian macrumors Penryn

    Eidorian

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    #24
    Apple just wants a cooler video card and less fan noise. It's rather annoying to have to overclock just to get retail stock speeds.
     
  25. Mercuric Oxide thread starter macrumors 6502

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    #25
    I think you might be right, but there's more to it. The speeds define the card, making it lower or higher can make it function as either a lower level or near higher level card in that series. With the stock speeds, it looks like this card is more of a Pro.

    Which would mean, you're right, ATi sent it to them that way. But they sent them a Pro, and Apple lied... (all speculation ;) )
     

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