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Thread: Dual 5870's

  1. #11
    Philadelphia
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    Re: Dual 5870's

    Thanks Ste\/e and Mr Hankey for the information on the plug.

  2. #12
    Philadelphia
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    Re: Dual 5870's

    I received this information from Zydor at the Moo message board on the processor running with both 5870's:

    "There is a long standing bug in OpenCL applications that affects dual GPUs (either on one card or two single GPU cards). The bug grabs a complete CPU Core for each GPU running. There is nothing the Project can do about it - has to be fixed at the OpenCL/AMD/NVidia side of life.

    Its slowly getting resolved, its been around for a few months now - only affects those with more than one GPU running on a box. AMD recently started testing a Linux fix, its not yet known when the Windows fix will be out. Spring next year would be a crude guess - its a nasty one to resolve apparently.

    Regards
    Zy"

  3. #13
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    Bryan's Avatar
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    Re: Dual 5870's

    A couple of basics ... just in case:

    1. Unless something has changed you WILL need the dummy plug.

    For MOO:
    2. Moo uses ALL ATI GPUs so you will only show 1 task running in BOINC.
    BOINC should show: running (??cpu + 2 ATI GPUs)
    3. The time reported in the task listing on the Moo project may or may not be accurate when running multiple GPUs. Click on the left column of a pending or valid wu (opens the wu std err file) and look at the START time and the STOP time and the difference is the actual time it took to do the wu. Your reported time MIGHT be double what this says. The wu has the correct time.

    What I mean by this: I recently put a new 6990 on a friends account and it was reporting 784s to complete a wu. After several days I detached/reattached and moved it onto my account. It started showing 1570s per wu while the std err file still showed it was completing wu in 784s. Same machine, same card, and same credits being produced ... it just showed double the amount of time in the projects tasks listing.

    4. When you have it running Moo, check the GPU loading using something like GPU-Z and you should see 95%+ loading on both cards.


  4. #14
    Cruncher Pete
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    Re: Dual 5870's

    Quote Originally Posted by Bryan View Post
    A couple of basics ... just in case:

    1. Unless something has changed you WILL need the dummy plug.
    It works in my machines without a dummy plug. I have two HD5870's in Crossfire mode. The cc_config states use_all_GPUs.

  5. #15
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    Re: Dual 5870's

    I think a lot depends on the Motherboard, some have to run the Dummy Plugs & others not ...

  6. #16
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    Re: Dual 5870's

    Quote Originally Posted by STE\/E View Post
    I think a lot depends on the Motherboard, some have to run the Dummy Plugs & others not ...
    Correct. Also Crossfire removes the need for a dummy plug as the cards are then technically one unit.


    Future Maker? Teensy 3.6

  7. #17
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    Re: Dual 5870's

    Quote Originally Posted by Fire$torm View Post
    Correct. Also Crossfire removes the need for a dummy plug as the cards are then technically one unit.
    ...even though BOINC still sees and treats them as two separate GPUs.
    "Don't confront me with my failures, I had not forgotten them" - Jackson Browne

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  8. #18
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    Re: Dual 5870's

    Does running them in crossfire mode reduce the efficiency? I remember a way back that you would lose some crunching power by running in CF mode. Maybe they fixed it.



  9. #19
    Philadelphia
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    Re: Dual 5870's

    Quote Originally Posted by Mike029 View Post
    Does running them in crossfire mode reduce the efficiency? I remember a way back that you would lose some crunching power by running in CF mode. Maybe they fixed it.
    I can't quote where I read it, but I seem to remember someone (one person) mentioning that cross firing them for boinc was not the way to go. I can cross fire them (one is a 2mb, other is a 1mb, if that matters).

    For what it's worth/not worth, my mother board is a P5W DH Deluxe.

    Personally, I enjoy all the discussion, lots of food for thought. I'm going to the local Radio Shack tomorrow to set up the dummy plug just in case. I've got 235.00 is the two GPU's (one sitting next to me on the desk ) so what is another dollar or so.
    Last edited by Philadelphia; 12-02-11 at 09:17 PM.

  10. #20
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    Re: Dual 5870's

    Quote Originally Posted by Philadelphia View Post
    I can't quote where I read it, but I seem to remember someone (one person) mentioning that cross firing them for boinc was not the way to go. I can cross fire them (one is a 2mb, other is a 1mb, if that matters).

    For what it's worth/not worth, my mother board is a P5W DH Deluxe.

    Personally, I enjoy all the discussion, lots of food for thought. I'm going to the local Radio Shack tomorrow to set up the dummy plug just in case. I've got 235.00 is the two GPU's (one sitting next to me on the desk ) so what is another dollar or so.

    Let us know how ya make out Phili. Being from New York, I won't hold it against ya. Giants, Rangers, Islanders, Yankees, etc (forget the other teams) OHHHH!!!!



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