Confirmed AMD Radeon HD 7970 GHz Edition Running on Mac Pro

Discussion in 'Mac Pro' started by blackwoodfx, Dec 11, 2012.

  1. macrumors member

    blackwoodfx

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    #1
    Confirmed working, AMD Radeon HD 7970 GHz Edition on OS X 10.8.3, Mid 2012 Mac Pro, no flashing required. Also confirmed working since 10.8.1 beta. Strongly believe this is here to stay. Beautiful hardware. Real-time playback of full-resolution 4K footage in FCPX. Also tested with Adobe apps and lots of GPU crunching. Stable. No issues at all.

    [​IMG]

    [​IMG]
     

    Attached Files:

  2. thread starter macrumors member

    blackwoodfx

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    #2
  3. macrumors 65816

    DanielCoffey

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    #3
    Excellent news. I am sure folks will want to see benchmarks vs the 5870...

    How did you handle the power requirements for the 7970? Isn't it 250W (PCI+6+8pin)?
     
  4. thread starter macrumors member

    blackwoodfx

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    #4
    No funky power management required. Used the dual 6-pins and the 7970 ships with a 6-to-8-pin conversion cable in the box. Snapped that on and the card booted right up. Still 50 watts under the safe limit.
     
  5. macrumors 6502a

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    #5
    What about EFI screen ?
     
  6. Bwa
    macrumors 6502

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    #6
    This is exciting! Can you say which vendor card you bought exactly?

    How about fan noise? Any idea if 3x30" monitors works?
     
  7. macrumors 65816

    DanielCoffey

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    #7
    There won't be one, of course. Not that it really matters for users of a single Windows partition if you use the BootChamp app.

    ----------

    Under what safe limit? The Mac Pro supplies 225W and the card draws up to 250W. The 6-to-8 pin adapters are risky when you are drawing more than the machine is rated to supply.
     
  8. thread starter macrumors member

    blackwoodfx

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    #8
    We've tested both the MSi Radeon 2PMD3GDS 'vanilla' HD 7970 and the XFX Double D HD 7970 GHz Edition FX797GTDFC. Both work perfectly although we prefer the XFX, of course.

    Noise is much better (ie. quieter) than the oscillating, loud, and generally more irritating GTX 570 that we had been running previously. Quieter than dual 5870's but louder than a single, 'Apple Stock' 5870.

    Yes, 3 monitors do work. Tested 3 Apple LED Cinema Displays in vertical (90 rotated mode) with 2 of the monitors connected to the mDP ports and 1 connected via the Atlona Dual Link DVI to Mini DisplayPort Converter (powered by USB). Worked perfectly.
     
  9. blackwoodfx, Dec 11, 2012
    Last edited: Dec 12, 2012

    thread starter macrumors member

    blackwoodfx

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    #9
    I think you're fuzzing math... The 6-pin is 75w and 8-pin is 150w. PCI slots offer combined 300w (450w total). Already tested with full burn-in render tests and real-work RED R3D 4K files (debayering and rendering for final).

    *But perhaps to your point, you can't stuff a Quadro in with this thing or think about SLI-mode (although why would you?). The Mac Pro can handle the 7970 perfectly well. Just play nice with your other PCI slots. eSATA and USB cards are fine. We've even got a RED Rocket in one of ours. But that's the red line.
     
  10. macrumors 65816

    DanielCoffey

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    #10
    The MacPro officially supports only 225W for a graphics card in a PCI slot with 2x6-pin connectors.

    This has been clearly discussed in the "FAQ about nVidia PC Graphics cards" sticky thread. I am not fuzzing anything.
     
  11. thread starter macrumors member

    blackwoodfx

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    #11
    And that's all this card needs from those connectors. 75w @ 6-pin and 150w @ 8-pin = 225w.
     
  12. macrumors 65816

    DanielCoffey

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    #12
    I assume you appreciate that plugging an 8-pin into the 6-pin motherboard header does not magically deliver 150W? It delivers the 75W from the header (but allows the card to draw more, exceeding the design spec of the 6-pin cable and traces).

    The TDP of the 7970 GHz Edition is listed as 275W. That is significantly over the Mac Pro's 225W limit which is made up of 75W from the PCI slot, 75W from the first 6-pin and 75W from the second 6-pin that you have put the 8-pin cable into.

    While your card does run, you are depending on the ability of the traces on the logic board to deliver the extra current that the card is drawing. In fact the card will probably be throttling itself down to protect the logic board since that model has the ability to do so.
     
  13. blackwoodfx, Dec 11, 2012
    Last edited: Dec 11, 2012

    thread starter macrumors member

    blackwoodfx

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    #13
    Same page. Not sure why you're suggesting I'm not aware of this. There's no magic here. It's pulling 75w+150w on those lines. However, it's not exceeding the design spec at all. In fact, the only difference between a 6 pin and an 8 pin connection is the number of grounds. Both use 3x 12v rails. The 6 pin has 3 grounds and the 8 pin uses 5. Pins 1-3 are hot, 4-6 are ground + 7-8 ground. So those two extra pins are grounds only. They tell the graphics card it's ok to draw 150w -- which it is. Exceeding the design spec? Not at all.

    The MP has a limit of 300w across the 4 PCI slots and that 8-pin adapter does, as you said, allow the card to pull down more watts. We're not exceeding the LB or the PSU or even uncomfortably close to it. There is nothing unsafe about running this card either. You're being quite a bit alarmist here.

    *Edit: The reason I keep pointing out the PCI lanes are 300w combined, is because that's how the LB is wired to power them; as a 300w lumped together channel. We're not overdrawing the lane and we're well within what's needed from the PSU. We're not putting the LB at risk with this setup. Your hard-and-fast ruling is just inaccurate, sorry. I suppose there's nothing wrong with a little level-headed consideration and people should be aware of these things, but in this case, it's unwarranted. Also, while the Tahiti 7xxx cards do throttle, they do so to keep temps down while you browse the internet or other mundane tasks that don't require full-draw. Much more similar to a mobile graphics card would to conserve battery-life and manage heat. Something a little more 'novel' for desktop solutions. I'm not fighting with my graphics card here. It's doing quite well. :)
     
  14. macrumors newbie

    Mr.Gurke

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    #14
    Is it also possible to run the HD 7970 GHz Edition in a MacPro 3.1 (are there some significant differences in between the 5.1 and 3.1 power supply systems anyway)?
     
  15. thread starter macrumors member

    blackwoodfx

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    #15
    I'm not sure, Mr.Gurke. While I did quite a bit of hacking around with the 4,1 MP (http://forums.macrumors.com/showthread.php?t=1076970), I haven't cracked open anything prior.

    A quick glance here doesn't raise any flags that might be an issue:
    http://en.wikipedia.org/wiki/Mac_Pro#Specifications

    I'd make sure you've got power supply with the same wattage as the 4,1-5,1-2 first, then make sure you have 2x 6-pin PCI cables and a 16x PCI Lane. If those three things check out, you should be in the clear.
     
  16. macrumors 6502a

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    #16
    There was no need to hack OpenCL for the >2GB VRAM limit ? Does that only affect nVidia cards ?
     
  17. macrumors 68030

    flowrider

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    #17
    ^^^^No, from all that is now known, the OS 10.8.3 beta removes the 2GB RAM limitation.

    Lou
     
  18. macrumors regular

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    #18
    So there is support for this card in 10.8.2?
     
  19. macrumors 6502a

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    #19
    You're missing the point though. That's 300W across four slots, or 75W per slot. One 6-pin cable provides an extra 75W. The second cable provides the final 75W for a total of 225W for one slot. You're pulling up to 150W from one of those cables, which is not in the 300W budget for all PCIe slots, it's from the separate connector on the motherboard. People have damaged their cards by trying to make an 8-pin connector work by using a 6-pin to 8-pin converter, trust me this has been discussed at length in many different threads. We're not just making **** up here.

    More power to you (no pun intended) if you want to ignore our warnings and run with a converter cable, but our standard advice for anyone using a card that has one or more 8-pin connectors is to drive it with an external power supply. Links in my FAQ thread with more details. Edit: Actually, I guess I haven't posted links to the discussion of how to rig up an external power supply yet. Should be easy to find with a bit of searching, someone posted a detailed guide on how to do it for both internal and external PSUs.
     
  20. macrumors 601

    ActionableMango

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    #20
    If an 8-pin to 6-pin adapter damages video cards, why would the video card manufacturer include one in the box? Doesn't that imply that at the very least, this one particular model video card should be okay with such an adapter?
     
  21. macrumors 6502a

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    #21
    Because it probably works fine when you connect one of the nice big fat cables coming out of a regular PC power supply? The major difference here is the fact that the supplemental power comes from the 2 low-profile connectors on the motherboard. These are designed for 75W each, and the power comes through the traces on the motherboard itself (not a dedicated cable from the PSU).

    The point we're trying to make is that the Mac Pro is designed for a maximum of one 225W card. You're in unsupported territory if you try and drive a card that requires more than that via the slot and power cables alone. You might damage the card and/or your entire system -- for example, there's a thread over on netkas.org where a guy tried to overclock his 300W GTX 680 super-overclocked board running on Mac Pro power alone, and ended up killing it. If you want to risk your $500 card or $2500 system, go for it. Personally, I'll stick with cards that fit inside the 225W power budget.
     
  22. macrumors 601

    ActionableMango

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    #22
    I don't want to do anything, I am happy with my 5770. I only ask out of curiosity.

    I would think the overwhelming majority of users presented with this card and this adapter would just hook them up and not know what TDP is or know anything about wattage rating of PCI lanes and motherboard traces. Without knowing any better, it seems like the logical thing to do.

    I'm not saying you are wrong, in fact, I believe you. But, if you are right, this manufacturer is being exceptionally dangerous by including such an adapter. There should at least be a big huge warning card or something.
     
  23. macrumors 65816

    DanielCoffey

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    #23
    Not really - the card doesn't say "Mac Supported" on it and for almost all PC uses, the supplied cable will be perfectly fine. It is just on Mac Pros with the traces on the Logic Board that it shouldn't be used.
     
  24. macrumors 6502a

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    #24
    Because the 7970 is not an official Mac card? It was never designed to work in a Mac Pro. Just like the GTX 580 was never designed to work in the Mac Pro, it also has one 6-pin and one 8-pin connector. Neither of these cards are specced to work inside a Mac Pro, and that's one of the many reasons why there aren't official Mac versions of these cards. Right?

    ----------

    Exactly this, yes.
     
  25. macrumors 604

    MacsRgr8

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    #25
    Please let Barefeats get this card!!

    I just NEED to know how this works in X-Plane 10!
     

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