OpenCL question

Discussion in 'Mac Pro' started by product26, Aug 7, 2009.

  1. product26 macrumors 6502a


    May 30, 2005
    Ok, I know it is early to be asking such questions BUT....

    With Open CL, is it possible to install additional graphics cards with no monitors plugged in and utilize their processing power?

    I recently flashed an evga 8800gt with the mac firmware, unfortunately before and after the flash the card does not run at 16x, it only works in a 8, 4 or 1x slot. If I get another 8800gt, flash it, and run both at 8x... perhaps I could benefit from having the spare card installed. I do enough video editing and encoding to want a lil more speed.
  2. 10THzMac macrumors 6502

    Dec 17, 2007
    There are three separate issues here.

    1. OpenCL should access multi GPUs as long as they are compatible, which includes Nvidia cards. I am using two 285s under Cuda in this way, and have seem some early demos of OpenCL that worked similarly. Only one card drives a monitor but both cards are accessible

    2. Another issue is your 8800GT flashing. You should get 16x and a link of 5 GT/s, which is what I get on my Mac edition 8800GT in an 08 Pro. Have you actually got a ROM large enough to hold the Mac firmware OK. Also which Mac Pro have you got - this does matter (EFI32 vs 64 etc).

    3. Your software would also need to be able to talk to one or more GPUs to use them...
  3. product26 thread starter macrumors 6502a


    May 30, 2005
    when I first got the card, before flashing, it would not run at all in my shuttle PC with one 16x pcie slot. The fans run full blast and there was no display. Same result with a computer at my office. Switching the office computer to sli mode (dropping the pcie to 8x) worked and allowed me to flash the card with the mac firmware. The card does have the larger rom size, verified before flashing. I have a mac pro 1,1. But that is irrelevant as the card was doing this before and after flashing the mac firmware, suggesting that it has a hardware issue, not firmware.

    After putting the flashed card in my mac pros second slot (set to 1x) I used the expansion slot utility to set slot 1 & 2 to 8x and it works perfectly. This is why I am wondering if I can add an additional card running at 8x and gain power via opencl. If this does indeed work. I will probably keep this card and pick up another to flash and hopefully get it to run at 16 x. I am pretty sure the expansion slot utility had a setting for one 16x one 8x and two 1x slots.

    I will be flashing the card with the latest evga firmware, testing again and flash back to mack to see if I can resurrect the cards ability to sync at 16x. (fingers crossed)

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