R9 280x question?

Discussion in 'Mac Pro' started by LMR80, Aug 24, 2016.

  1. LMR80 macrumors member

    Joined:
    Jul 1, 2016
    #1
    hi,

    I've decided to put an r9 280x into one of my Mac pros.

    I was wondering if anyone knew which non-reference cards work (or if they all do)
    And also which power cables I need?
    I say a video that stated you can accidentally buy the wrong ones because of the wiring, and also the wrong length.
    I know it's 6 to 6 pin and 8 to 6 pin that you need.

    I found these two, but I don't know weather they'd be right:

    http://www.ebay.co.uk/itm/8Pin-to-M...148942?hash=item280afe978e:g:DS0AAOSw9mFWMmS7

    http://www.ebay.co.uk/itm/Mini-PCIe...560513?hash=item210861fe01:g:1fEAAOSwHaBWk4Ym

    I wouldn't be flashing it because I don't need a boot screen.

    Thanks!
     
  2. Beno201 macrumors member

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    Aug 10, 2016
    #2
    I think the standard length for the cables are fine
     
  3. Ph.D. macrumors 6502

    Joined:
    Jul 8, 2014
    #3
    You want a non-reference card whose output ports match the reference cards, most particularly having 2x mini-display ports. I have an MSI R9 280X ("gaming G" "Twin Frozer") and it works well. But some will not work, so be careful and confirm your choice.

    I have not flashed mine, though I did remove the R17 resistor for the extremely minor speed improvement that hack may provide.

    Mine came with a 6-8 pin power adapter, and I also had a spare power cable lying around, so I'm not sure if your choices on that are correct or not.
     
  4. Beno201 macrumors member

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    Aug 10, 2016
    #4
    so what cables do you need to connect the card?

    Thanks
     
  5. LMR80 thread starter macrumors member

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    Jul 1, 2016
    #5
    Thanks, that's good to know.

    I was thinking of getting the MSI card if it was supported, anyway.
     
  6. Ph.D. macrumors 6502

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    Jul 8, 2014
    #6
    Two specialty power cables, most often one 6-pin plus one 8-pin.

    Use mini-display port cables to your monitors.
     
  7. LMR80 thread starter macrumors member

    Joined:
    Jul 1, 2016
    #7
    just bought the card.
    The one I've bought is boxed and comes with a 6 to 8 pin, and a 6 pin to x2 molex.

    Should they work?

    Thanks
     
  8. Beno201 macrumors member

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    Aug 10, 2016
    #8
    So it's a 6 to 6 and an 8 to 8?
     
  9. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #9
    Your cMP do not have molex. Also, you need MINI 6pin to 6pin, and MINI 6pin to 8pin. In fact, you have the right cable (link) in your original post.

    However, be careful that some 280X can pull more than 120W from the 8pin when under stress. That will shut down your cMP. If that happen, don't panic, most likely nothing break. But you better stop doing that task until you solve the power issue.

    e.g.
    1) Do the Pixlas mod
    2) power the card by 2x mini 6pin -> 8pin + 2x SATA -> 6pin
    3) balance the loading between the mini 6pin by making a bridge
    4) use another PSU
    ......
     
  10. LMR80 thread starter macrumors member

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    Jul 1, 2016
    #10
    Oh right, so one mini 6pin to 6pin, and a mini 6 to 8 pin.

    The one I've ordered is the MSI model, will that be an issue with the power consumption?

    Thanks for the links, I'll give those a read through.
     
  11. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #11
    Don't know, it almost vary from card to card. Also, it depends on how you use it. If you use it to run Furmark, there will be a high chance that you hit the limit. For most normal usage (e.g. video editing, or gaming), the card should work fine without any issue.

    If you have to buy 2 cables anyway, consider the bridge method.

    2x mini 6pin -> 8pin -> 2x (6+2)pin. That should be a better method then mini 6->6, and a mini 6->8.
     
  12. LMR80, Aug 25, 2016
    Last edited: Aug 25, 2016

    LMR80 thread starter macrumors member

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    Jul 1, 2016
    #12
    Well I'm just using it for gaming mostly, so hopefully it'll be alright.

    For the bridge method:
    When you say 2x, that's TWO mini 6 to 8pin cables, right?

    And as for the second cable, not quite sure what you mean, sorry

    I'd also be a little concerned about doing a soldering job on a brand new card, I'd rather avoid unless necessary

    Thanks
     
  13. h9826790 macrumors 604

    h9826790

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    Location:
    Hong Kong
    #13
    1st cable - dual mini 6 pin -> single 8pin
    2nd cable - single 8pin -> dual 2+6pin

    No, I am not recommending you to solder your card, but if you read through that post, the above 2 cables should able to achieve the same thing.
     
  14. LMR80 thread starter macrumors member

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    Jul 1, 2016
    #14
    Right I see.
    Just had a lot for the cables, and the only ones I can find are really expensive, so I think I'll just go with the normal ones, and if I did run into any problems (which it sounds like I won't) I'll do the bridge method.

    So both cables in the links I provided will work?

    Thanks
     
  15. h9826790 macrumors 604

    h9826790

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    #15
    They should work
     
  16. LMR80 thread starter macrumors member

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    Jul 1, 2016
    #16
    Cool, thanks for the help
     
  17. Ph.D. macrumors 6502

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    Jul 8, 2014
    #17
    Though I have and use one, I think the 280x is just barely over the limit for the cMP on the stock power sources, meaning that it will run perfectly fine for 98% of stuff, but it might catch you out once in a while.

    My 3,1 with an MSI 280x has had zero problems running everything using the two 6-pin motherboard supplies and with a 6-pin to 8-pin converter for one. That included benchmarks, though I'm not sure I ever ran Furmark. However, there was one exception: When playing one game, it would occasionally crash - sometimes hard (i.e., more than just the game itself would sometimes crash). That's conceivably from drawing too much power (the hard crashes). The computer will try to protect itself, and it never caused any damage, but it certainly did make me wonder. I'd second the suggestion to "burn it in" by running Furmark for a half-hour or so and seeing if it causes any trouble for you.

    (I've since moved the few games I play to a faster Linux box - Skylake 6700k plus GTX 1070 - so the above is no longer an issue for me.)
     
  18. Beno201 macrumors member

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    Aug 10, 2016
    #18
    Interesting
     

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