7970 6GB in Mac Pro 5,1

Discussion in 'Mac Pro' started by MerryPop-Ins, Apr 29, 2014.

  1. MerryPop-Ins macrumors newbie

    Joined:
    Apr 29, 2014
    #1
    I've spent the last two months trying to figure out how exactly to get a Sapphire 7970 6GB (http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1157&pid=1483 &lid=1) working in a 2013 Mac Pro 5,1 running 10.8.5. Others have reported success with this card and just about very other 7970 variant, but I've been through unending nonsense just getting information about and procuring all the right components and connectors to wire this thing up, as I'm reluctant to use 6-pin to 8-pin power adaptors and run the risk of burning something out. Despite this, I'm unable to get the card working at all - fans don't spin, LEDs don't light up, Mac doesn't boot... Nothing. There's clearly something I'm still missing. I've missed a whole lot of things during this little saga, and I've had to learn quite a lot quite quickly - dozens of hours looking for information about this subject that I would have thought would be easy to find but wasn't, with plenty of little caveats that are so easily missed. I'll skip all the ridiculous details and simply explain where I'm at now, so I can get past this last little whatever-it-is I seem to still be ignorant about.

    Right now, I've got an additional PSU (http://www.newegg.ca/Product/Product.aspx?Item=N82E16817151099) sitting on top of the case, with two PCI-e 6+2-pin connectors running to the card, which is seated in the x16 PCI-e slot. The PSU's power switch is set to I (on), but it doesn't seem to be drawing any power. Here's where I may be missing something. Does the PSU require something else to tell it to begin doing its thing? I got this PSU as a replacement for a previous PSU I'd purchased for the 7970, which had no switch at all and required power from a 4-pin Molex to tell it to begin drawing from AC, and since Molex isn't included with the 5,1... Ehhh.... This new PSU was purchased specifically because it has a simple power switch. Now it seems I may have just thrown my money out the window twice on two PSUs. Does this thing require a blood sacrifice or some sort of dance? What's not right?

    Alternately, all I can think of is that the card is trash and a crooked eBay vendor has now gotten off scot free, considering how long it's taken me just to determine that the card isn't working - far too late for buyer protection to still be applicable.

    Help?
     
  2. xcodeSyn macrumors 6502a

    Joined:
    Nov 25, 2012
    #2
    You need to read this article about using the paperclip trick to power up the PSU without motherboard. Also you need to upgrade to Mavericks to recognize the 6GB VRAM as shown here and explained in posts made by KBS756 in this thread.
     
  3. MacVidCards Suspended

    Joined:
    Nov 17, 2008
    Location:
    Hollywood, CA
    #3
    I would love to hear a full and complete "6GB 7970/R9 280X works perfectly" story.

    You do indeed need to have all pins powered and the extra power supply needs to be told to "turn on"

    If all the wires are black find some high res pics of a regular cable like that and look where green and black wires are and jam a paperclip in those same wires. Their location hasn't changed in like 15 years so shouldn't be too hard to figure out.

    In short, I got a 7970 Sapphire 6GB to test. Was a small fortune and I was able to do the 2.0 mod and add an EFI. Nothing but crashes and freezes anytime OpenCl gets called, even in recent 10.9.3 Betas.

    Recently had a guy bring a R9 280x 6GB for modding. I put a nice EFI on it and flashed, and the OpenCl business was fixed.

    But he got back to his Studio and says that it doesn't work well using Pro apps with the EFI. If he lives without boot screen, it works better.

    There is a third gentleman who posted in a prominent pro board about using a 6GB R9 280x. I wrote to him asking if he had any of these issues. Instead of just writing back with "It works great" or "it crashes and freezes" he sent me a phone number to call him to discuss it. Not being a phone person, I may never know what he was going to tell me.

    In any case, bust out a paperclip and let us know. There is a 7970 EFI at Netkas that works with the card. (I wrote and posted it under my nom-de-plume there)
     

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