Imac Alu gpu: 2600Pro or 2600XT

Discussion in 'iMac' started by delville, Nov 26, 2007.

  1. delville macrumors newbie

    delville

    Joined:
    Oct 10, 2007
    #1
    Hi,

    Can someone in this forum confirm with 100% certainty that the gpu in the new iMac Alu is a 2600XT and not a 2600Pro?

    There is quite a bit of gaming performance gain if it is a 2600XT.

    Thank you.

    Regards,

    Delville:apple:
     
  2. flopticalcube macrumors G4

    flopticalcube

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    #2
    Its an XT that has been downclocked.
     
  3. Fletchzky macrumors member

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    Nov 25, 2007
    #3
    WTF? Why would they do that? Heat? And who is responsible for that? Apple or ATI?
     
  4. flopticalcube macrumors G4

    flopticalcube

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    #4
    Probably ATI at Apple's request. Most likely a heat issue.
     
  5. Vocalvoodoo macrumors newbie

    Joined:
    Nov 22, 2007
    #5
    If I remember correctly, in Windows it says the card is an XT. That would seem to suggest the Pro is an underclocked XT. Although XP could be reporting it wrong.

    Too bad the iMac doesn't have a 'real' video card though. At least as an option. :(
     
  6. AppleWoW macrumors regular

    AppleWoW

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    #6
    If your nifty with a computer tho you can OC the card every time you go into windows if you want more power :S
     
  7. Fletchzky macrumors member

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    Nov 25, 2007
    #7
    Is there a utility that allows you to do this?
     
  8. nickf macrumors member

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    Oct 2, 2007
    #8
    Woah, easy there Tiger.

    It might be a downclocked XT. Then again, it could also be a tweaked 2600Pro. Only Apple (and ATI) know for certain.
     
  9. flopticalcube macrumors G4

    flopticalcube

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    #9
    ATITool will do it but you need to increase the GPU engine by 7MHz and the VRAM by 9MHz steps.
     
  10. Eidorian macrumors Penryn

    Eidorian

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  11. flopticalcube macrumors G4

    flopticalcube

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    #11
    Chip ID says its an Mobility 2600XT. Benchmarks put it somewhere in between a 2600Pro and a 2600XT. I think its fairly safe to say its an underclocked XT (or at least performs like one). The only real difference between a Pro and an XT is the GPU clock and the VRAM (XTs can use GDDR4).
     
  12. Fletchzky macrumors member

    Joined:
    Nov 25, 2007
    #12
    I wish someone would do a gaming benchmark test in bootcamp with the card overclocked vs. "regular." I really don't like the idea of overclocking a card in a machine where I can't swap it out if necessary.
     
  13. flopticalcube macrumors G4

    flopticalcube

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    #13
    Those who have overclocked it don't get very far before instability sets in. Maybe 10% increase. Not really worth the risk, IMHO.
     
  14. Fletchzky macrumors member

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    #14
    Yeah I was thinking instability from OC would come into play, given the enclosure.
     
  15. SaSaSushi macrumors 68040

    SaSaSushi

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    Takamatsu, Japan
    #15
    Yeah, I definitely think the risks outweigh any potential benefits from even a 15% or 20% increase if that were possible. The iMac is a very compact unit and there is a reason Apple clocked the card the way they did.

    Still, the games I run (Half-Life 2, Bioshock, Counterstrike: Source, etc) at the native resolution of the 24" display (1900x1200) get very acceptable framerates with medium to high detail settings.

    If you're looking for a top-end gaming machine you shouldn't be thinking of an iMac to begin with.
     
  16. AlexisV macrumors 68000

    AlexisV

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    Manchester, UK
    #16
    Well, to be honest, there is no high end Mac gaming machine, so it's iMac + 2600 or OS X and nothing.
     
  17. Eidorian macrumors Penryn

    Eidorian

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    #17
    In before Mac Pro.
     
  18. Superman07 macrumors 6502a

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    Aug 28, 2007
    #18
    +1!!

    I'd go one step further and say you shouldn't even be looking at a Mac! Granted you can run Windows on a Mac these days, but I think if you want a serious gaming machine you're still better off going with a native Windows machine. Besides, you won't be getting an SLI setup out of an iMac either.
     
  19. snickelfritz macrumors 65816

    snickelfritz

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    #19
    The XT and Pro are probably the same chipset.
    The difference is in the maximum stable clock frequency.
    (this is probably determined during QC tests, where the chipsets are sorted.)

    Apple is probably using XT-rated chipsets/RAM clocked down to a specific frequency that minimizes core temps and ensures stability while still reaching the target performance baseline.
     
  20. flopticalcube macrumors G4

    flopticalcube

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    #20
    In Mobility-land there is no Pro chipset, only XT and vanilla. The chip vendor ID for the iMacs is for a Mobility 2600XT (9583). The vanilla Mobility 2600 carries a different vendor ID (http://ati.amd.com/developer/vendorid.html). The ASIC themselves are the same, however. My guess is that Apple wanted to mask the fact that it was using a laptop GPU so it called it a "Pro" seeing as the performance was not unlike a GDDR3 equipped desktop PRO.
     
  21. psonice macrumors 6502a

    Joined:
    Jul 22, 2005
    #21
    From my understanding, it's an underclocked XT (the chip ID confirms it), and apple label it a PRO because people would complain if they knew it was underclocked. If it's called PRO but actually goes a bit faster, people are happy.

    As to why it's underclocked, I think it's a combination of power and heat. Heat is obviously a major issue in the space available, but power must be tight too considering that the PSU is built into the same case. Which makes me wonder - would you get better overclocking results if you remove a stick of RAM, or underclock the CPU to draw less power there? Obviously neither would be very good for performance, but it'd be interesting to find out :)
     
  22. RevToTheRedline macrumors 6502a

    RevToTheRedline

    Joined:
    Sep 27, 2007
    #22
    It's a box of cereal

    You guys can say anything you want, nobody really knows for sure. Except ATI/Apple.
     

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