Dual GPU Mac Pro 2008 - how to power?

Discussion in 'Mac Pro' started by r6mile, Feb 3, 2016.

  1. r6mile macrumors 6502

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    #1
    Hi,
    I am considering upgrading the Radeon 5770 in my 2008 Mac Pro for a GTX 570. However, I want to still have the option to get an EFI boot screen without having to open up the Mac Pro every time. I was planning on putting the GTX 570 in the PCIe 16x slot where the Radeon is at the moment, and put the Radeon in a 4x slot (as its purpose will really just be to get a boot screen when it's needed).

    My question is how can both cards be powered. The GTX 570 needs two 6-pin power connectors, while the 5770 needs one. But AFAIK, the motherboard only has two ports, so I'm one short. Is it possible to power both cards?

    Thanks.
     
  2. Draeconis macrumors 6502a

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    May 6, 2008
    #2
    You'll need an additional PSU which you can install in the 5.25" ODD bay.
     
  3. r6mile thread starter macrumors 6502

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    #3
    Is that really the only way? I already have two superdrives so there are no free 5.25 bays.

     
  4. Draeconis macrumors 6502a

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    #4
    You could also heavily modify your existing PSU, but that's quite an involved procedure. Please search these threads to see people's attempts at it.
     
  5. nigelbb macrumors 6502a

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    Dec 22, 2012
    #5
    The simplest solution would be to sell the 5770 & buy a Mac nVidia GeForce GT 120 or ATI Radeon HD 2600 XT as neither of these cards requires an extra power lead.
     
  6. r6mile thread starter macrumors 6502

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    #6
    Thanks both for your help. It looks like the best solution will be to sell the 5770, and either replace it for one of the cheaper cards (which are not actually that much cheaper on eBay), or skip the GTX 570 and go straight to a GTX 680 which can be flashed for mac for a single GPU setup.
     
  7. nigelbb macrumors 6502a

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    Dec 22, 2012
    #7
    That would be my recommendation. I thought that you already had the GTX570.

    I've just upgraded from GTX570 to GTX680 in two Mac Pros. The new card is quieter & allows up to four monitors to be connected with 4K@60Hz via DisplayPort & after flashing has an Apple boot screen. Actually flashing the card was easy but installing Windows that was a struggle.
    I got an eVGA GTX680 like this one although I paid about £140 http://www.ebay.co.uk/itm/EVGA-GeFo...736941?hash=item2a6081aa6d:g:1cUAAOSwa-dWrJr-
     
  8. JimmyPainter macrumors member

    JimmyPainter

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    Nov 13, 2015
    #8
    The amount of you budget is the deciding factor ... a few of the Best options to me would be ..

    1. AMD 7950 Mac Addition
    2. Ati 2600 boot card w/ PC 7970 which is my solution and faster than stink
    3. Macvidcards . flashed 7970
    or if you need CUDA / nVidia
    1. 680 Mac addition
    2. GT120 Boot card and PC GTX960/970 depending on money
    3. Macvidcards flashed whatever you can afford.
    or ... if you got's the money and know that a 12 core cMpro 5,1 is in your future ..
    wait just a sec till the new cards come out later this year and get you 2 GTX 970's for cheap from some "NEW" Gamer friend your gonna meet soon who's gotta have the latest and greatest. These 2 Cards have a Great Youtube video on how to Power internally and can migrate up when you move to the newer 5,1.
    I will most likely go to 5,1 if the 6,1's don't get cheaper and use my CDROM bay Power supply I am not using yet to Crank me up a couple of MONSTER 7990's. I don't NEED any of this, my 3,1 with my 7970 is plenty for what I do.
     
  9. r6mile thread starter macrumors 6502

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    #9
    Well, yesterday I bought for £25 a GTX570 from eBay, which was sold as 'untested, maybe working', and it should arrive this week. So if it works, I could just sell that on for a bit more, and if it doesn't, resell it as 'not working' and hopefully get my money back. I want to keep things simple and because of the limited power connectors, having to swap GPUs if a boot screen is ever needed seems like a bit of a pain.
     
  10. nigelbb macrumors 6502a

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    Dec 22, 2012
    #10
    A GTX680 with a boot screen is more convenient but the GTX570 is an excellent card too. It's a real bargain as it's much cheaper used than the GTX680 & although it's a bit hotter & noisier the performance is pretty much the same.
     
  11. r6mile thread starter macrumors 6502

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    #11
    Do you still keep a Mac GPU in case you need a boot screen? Is there any way to boot into recovery or an install dvd without a boot screen (does anything happen if you press command + r on startup?)?

     
  12. nigelbb macrumors 6502a

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    #12
    The ATI Radeon HD 2600 XT that shipped with the Mac Pro gave me the Apple boot screen when I was using the GTX570. I recently upgraded to a GTX680 & flashed it with the MAC firmware to give me the boot screen.
     
  13. r6mile thread starter macrumors 6502

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    #13
    Thanks a lot niqelbb. If the GTX 570 on its way works (fingers crossed, I took a gamble on eBay but for the price I thought it was worth it), I might just sell the 5770 and get one of the low-end Apple cards.

    Is anyone aware of a list of Official Apple graphics cards that do not require auxiliary power? I don't really care about performance since its only purpose will be to give a boot screen when needed, so looking for the cheapest. I am aware of the Radeon 2600XT and the Geforce GT120. I imagine the 7300GT used in the 1,1 and 2,1s would work too? Are there any other ones?

    P.S: Sorry if this sounds like a stupid question, but I'm not familiar with how multi-GPU set ups work. Do you just have the monitors plugged in into the PC card (and not get a boot screen) most of the time, and then just plug in the monitors to the Apple card when you need a boot screen?
     
  14. Fl0r!an macrumors 6502a

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    #14
    I think the 7300GT is EFI32, so it won't show a bootscreen in your EFI64 Mac.

    You could power your HD 5770 from SATA/IDE power connectors if you don't need all of them. Additionally the GTX 570 could be flashed, MVC offers this. DIY would require replacing the EEPROM with a larger one.
     
  15. r6mile thread starter macrumors 6502

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    #15
    Very good point about the 7300GT, I hadn't considered that.

    As for the power connectors, both 5.25 bays are occupied by Superdrives, but 2/4 of the 3.5 hard drive bays are free. Is this what you meant? If so, is this the sort of cable I would need? http://www.amazon.co.uk/Startech-Po...=8-1&keywords=SATA+Power+to+6-Pin+PCI+Express

     
  16. nigelbb macrumors 6502a

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    Dec 22, 2012
    #16

    Don't forget that you need the specific Mac version not just the generic PC version that can be found much cheaper.
    Personally I had the card sitting on a shelf as it seems pointless having it sitting in the machine consuming power & chucking out heat when it's never used besides which you could have all the PCIe slots used e.g. GTX570 + USB3 + PCIe SSD + eSATA. It only takes a minute to fit if you ever need an Apple boot screen.
     
  17. JimmyPainter macrumors member

    JimmyPainter

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    Nov 13, 2015
    #17

    I agree whole with Nigel. IF ... your system is good and stable and your not going to be reconfiguring on a regular basis ... Get you another 6 pin cable. Load the nVidia Drivers and CUDA. Pull the 5770. Slap in the GTX570 and go to town. I had a "PC" GTX260 216 core before my 7970 and it ran like crazy ... loved it. Just wanted more OpenCL. A GTX950 ti is a cheap little monster and uses alot less juice if the 570 doesn't make you happy.
    --- Post Merged, Feb 5, 2016 ---
    Put the Stupid 5770 back in there if things get sideways. Fix your workstation. Then slap that killer little 570 back in there.
     
  18. Zeke D macrumors 6502a

    Zeke D

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    #18
    I was experimenting with a 780Ti that required a 6-pin and an 8-pin, I just ran an EVGA 600w PSU, and fished the 8-pin leads through an i/o plate. I just bridged the ATX-power on and ground to power the card. I suspect the same would work for dual GPU setups - power both the 6-pin connectors off the motherboard and power the 8-pin connectors with an external PSU.
    --- Post Merged, Feb 5, 2016 ---
    Do you have a link to a suggeted 5.25-bay PSU for powering the GPU?
     
  19. r6mile thread starter macrumors 6502

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    #19
    Thanks guys. The 570GTX that I ordered as 'untested' is fully functional, and I will swap the 5770 for a GT120 that is on the way.
     
  20. JimmyPainter macrumors member

    JimmyPainter

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    #20
    Cool ... Send us some Benchmarks when you get it setup :)
     
  21. r6mile thread starter macrumors 6502

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    #21
    Turns out the card was not fully functional and causes the mac to randomly crash and reboot, so I've got another gtx 570 on the way.

     
  22. r6mile thread starter macrumors 6502

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    #22
    Turns out my 3,1 Power Mac is one of those that has stability issues with the GTX570 when installed in PCIe slot 1. This is something that I would not have discovered were it not for this forum. Very strange and unfortunate issue, but the card is now installed in Slot 2 and working well. This means I've lost one of the PCIe slots, which means bye bye eSATA card that I would likely never have used anyway. There is also a GT120 for when boot screen is needed. Both cards are working well!
     
  23. MacVidCards Suspended

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    Nov 17, 2008
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    Hollywood, CA
    #23
    There are 2 models of 570.

    The ones with the fan at back end will frequently not allow the GPU fan to engage, in slot 1, causing the overheating you noted.

    The GTX570 with fan in center fix this issue. They also have a DP port, which gives greater flexibility in display output. It may be worth your time to find the other type of 570 to regain your lower slot. Having the 570 flashed would allow you to sell the GT120 to cover the cost.
     
  24. r6mile thread starter macrumors 6502

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    #24
    See below - picture number 1 was the first 570 (a 570 HD, with a DisplayPort), while picture number 2 has the fan at the back and is now the one installed. Both have the fans in different locations, but have the same issue of random crashes and reboot.
     

    Attached Files:

  25. MacVidCards Suspended

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    #25
    Do this, leave side panel off.

    The 570 with fan at end will spin fan at boot, but it will stop at desktop, in slot 1 of a 3,1. The one with fan in center will not do this.
     

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