Overclocking iMac Gfx

Discussion in 'iMac' started by DerKommissar, Dec 3, 2007.

  1. DerKommissar macrumors newbie

    Joined:
    Dec 1, 2007
    #1
    Anyone successfully over clock the 2600pro/xt chip in the new iMacs from the mac side? Seems like it can be done on the pc, but the settings revert to stock when you reboot the mac os. Is that correct? I've looked for this info here and seen hints about it, but no direct answer.
     
  2. adamfishercox macrumors 6502

    Joined:
    Aug 15, 2007
    #2
    I don't know how, but I'd be careful doing it. The iMac doesn't need much more heat ;)
     
  3. flopticalcube macrumors G4

    flopticalcube

    Joined:
    Sep 7, 2006
    Location:
    In the velcro closure of America's Hat
    #3
    On the PC side, instability sets in at around 5% GPU increase. Not really worth it, IMHO.

    This is the only tool I know of but it doesn't even support the X1600 yet, never mind the HD2600.
     
  4. Sun Baked macrumors G5

    Sun Baked

    Joined:
    May 19, 2002
    #4
    Unstable and freezing at regular temps, or seems that some of the memory may have been a problem.
     
  5. cxc macrumors member

    Joined:
    Nov 30, 2007
    Location:
    Cologne, Germany
    #5
    Even if possible the 2600 just doesn´t have enough raw pixel processing power to allow for high resolution / high detail gaming. The performance or rather lack thereof under OS X (sluggish 10.5.1 animation and such) is due to underperforming drivers. Under Vista the itunes visualizer delivers 30% more fps than under os x. There is some heavy tweaking ahead of ati/apple.
    It´s not all bad though as unloading of h264 decoding under 10.5.1 seems to work. Playback of 1080p content yielded cpu loads around 35% per core.

    ceres
     
  6. Muncher macrumors 65816

    Muncher

    Joined:
    Apr 19, 2007
    Location:
    California
    #6
    You nailed it. As :apple:/ati release more driver updates, you'll see performance jump in small bursts. You can overclock it though, I believe, and as it's already underclocked for low noise, upping your fan speeds through something like smcFanControl should keep heat at a decent level. I don't know anything about resetting at reboots, though, 'cause I've never tried it.
     
  7. DerKommissar thread starter macrumors newbie

    Joined:
    Dec 1, 2007
    #7
    Yea, I've used that tool on my old G5, but he does not appear to be updating it anymore. I would think there is room to over clock. I don't trust that there will be significant updates to the drivers. Apple does not have a good history with that. Most of the time, apple updates to drivers tend to fix quality issues by slowing down the chip. They really are not interested in spending engineering time on speeding things up.

     
  8. flopticalcube macrumors G4

    flopticalcube

    Joined:
    Sep 7, 2006
    Location:
    In the velcro closure of America's Hat
    #8
    Which is a shame because the last few driver updates for XP from ATI have been very good at improving both performance and stability.
     
  9. DerKommissar thread starter macrumors newbie

    Joined:
    Dec 1, 2007
    #9
    Well, let's hope they pass that along to us...

     
  10. cxc macrumors member

    Joined:
    Nov 30, 2007
    Location:
    Cologne, Germany
    #10
    CPU and GPU are sharing the same heatpipe in the AL iMac so I´d advise against overclocking. Even reaching true xt speeds will likely not lead to tangible performance increase. There is a mobility xt in there for a reason. Likewise I don´t know if vga ram is actively cooled or not.
     

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