Mac Pro 5,1 PSU options for GPU

Discussion in 'Mac Pro' started by CRAYONSEED, Apr 19, 2019.

  1. CRAYONSEED macrumors newbie

    Apr 19, 2019
    Long time lurker here. I'm in video production, and have a Mac Pro 5,1 that I've upgraded with SATA 6g SSDs, 32GB RAM, USB3 and a GTX 1080. I'm pretty frustrated with the situation with Apple and Nvidia web drivers and not being able to upgrade to the latest OS, and having issues even installing security updates.

    I've all but decided to make a move from my 1080 to a Vega 64, but I use this machine for work and am not comfortable modding my PSU or having an external PSU with a separate power switch and cord, requiring some kind of launch sequence to turn my computer on (from what I've read).

    I've been researching and there's a lot of information out there; so much that I wanted to ask a couple of definitive questions:

    -Can I buy a Pixlas modded PSU, or pay someone reputable to mod mine? This seems like the easiest solution if it exists (my searches turned up nothing).
    -Is there an easy way to take power from the optical bays without splicing or soldering? I can use an external drive the few times I actually need to read a disc.

    Thanks for reading and thanks in advance for responding!
  2. crjackson2134, Apr 19, 2019
    Last edited: Apr 19, 2019

    crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
    You might be able to get someone to do the mod for you, but I doubt you'll find a "Reputable" modder (do they even exist). It's really not as hard as you may think. Just read, and look at the pictures. An 8th grader could do it. I don't know of anyone who sells a PRE-MODDED PSU. That would be cool.

    Yes, you can take power from the optical bays using splitter cables, do a search and read up on it. I'm not sure how much power that would provide, nor do I know about the power requirements for the GPU you want. Do your due-diligence and read up on it. The information is already here in the forums. Just use the search option.–-gpu.2173579/
  3. CRAYONSEED thread starter macrumors newbie

    Apr 19, 2019
    Thanks for responding! I'm capable of modding and doing the work, but it doesn't seem smart to in my case. I've already done a ton of research and am not comfortable with any solution that requires messing with electrical on a machine that's critical for my income. Nothing to do with how simple or complex it is and presumably the 8th grader in your example doesn't depend on their computer for work :)

    Yes a pre-modded PSU would be cool, and I'm surprised no one offers it. I'd pay to just have a PSU I can swap and plug in a new GPU and be done.

    I've used the search function (extensively; both here and the mac pro reddit), but have found so much information that spans years that it's hard to parse out exactly what is needed to take power from the bays and whether it will be enough to power a Vega 64 under full load.

    I guess after all the reading and research I've done, what I'm looking for is a definitive, guaranteed-to-work solution that is no more complex than a standard system build. If that doesn't exist I'll have to move to another machine altogether.
  4. bsbeamer macrumors 68020

    Sep 19, 2012
    External PSU is the easiest non-modify way to achieve most of what you want. It just needs to be turned on before your computer and treated like PCIe expansion boxes, which is another legitimate option depending on your budget.
  5. crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
    Have you considered purchasing a PSU from eBay, then purchasing the cable kit, and doing the MOD to that PSU yourself.
    When it's finished, all you have to do is make the PSU swap. Seems a good option I would think.
  6. CRAYONSEED thread starter macrumors newbie

    Apr 19, 2019
    Thank you both for taking the time to respond! So it seems like, based on my research and your responses, the viable options are:

    -Pixlas mod in some form.
    -External PSU.
    -Go with a less power hungry AMD card like the 580 (power downgrade) or a WX 9100 (expensive).
    -Get rid of this setup and grab an iMac or Mini and eGPU.
    -Deal with Nvidia web drivers in High Sierra and the headache that brings, and pray they release Metal 2 Nvidia web drivers that allow me to upgrade to Mojave.

    Am I missing anything?

    PS - Running power from the sata ports seems like that will not be enough power for the Vega cards. See here:
  7. bsbeamer macrumors 68020

    Sep 19, 2012
    You may see some reports saying something else, but Vega's really need more power than MP5,1 can typically provide naturally... so YES, you need to supply that power in some fashion.

    IF you are not comfortable providing that power with modifications to your MP5,1 an external PSU is about the only option that would work for your needs. Powered via PCIe expansion (which is basically eGPU without TB involved for this purpose) would also work, but may be cost prohibitive to explore.

    Sapphire Pulse RX 580 8GB is recommended by APPLE directly and 100% works with dual mini 6-pin to standard 8-pin power cable.

    I find it hard to recommend any NVIDIA GPUs for macOS usage these days. It's a poor "investment" and on life-support for macOS. If you're running in Windows only or fine with staying on High Sierra, that's an entirely different story.
  8. AlexMaximus macrumors 6502a


    Aug 15, 2006
    A400M Base
    There is on other option that might work here. You could go with a Vega 56 Red Dragon, - which at least on paper still would have the same power as the iMac Pro standard model card. It's a lot faster than the 580. I have read somewhere at the forum that you can use two SATA Power cables and maybe some other tricks such as an EVGA Power Link to power it without the Pixlas cable mod. Others with more experience may chip in here regarding the Vega 56. The Red Dragon looks like a very long card to me, and the cooling seems real great. Most Vegas 56 have a smaller PCB and therefore run cooler and quieter than Vega 64s, needing one 6pin and one 8pin power only.
    Regarding a pre-configured original PSU with a Pixlas mod-idea, - it would be possible. But it would be a major pain for the buyer to fiddle the cable with the already crimped contacts through the very tight corner in the front. I did that once, but it takes forever and lots of skill. The fiddling takes almost longer than a whole Pixlas mod altogether.

    As a Pixlas Vega 64 Limited Editon user, I have to say -it was wholeheartedly worth it for me. Mojave runs great and very fast with a Vega 64. I really loved my older flashed 980Ti with boot camp support, but looking back it was really worth it to bring the machine into the new world of AMD/Metal/Mojave. You are on the right track, stay on course and sell your Nvidia as soon as possible. I would go all Vega 56 in your case.

    Good luck!
  9. Mac Hammer Fan macrumors 6502a

    Mac Hammer Fan

    Jul 13, 2004
    I didn't have any issues with the GTX 980 and High Sierra. My system was rock stable and all security updates went well. I used screensharing to install the new nVidia drivers. Now I have 387.10.10.10. 40.124. But I had troubles in Sierra after putting the computer to sleep and wake up again. Are the Pascal drivers less reliable?
  10. CRAYONSEED thread starter macrumors newbie

    Apr 19, 2019
    Yeah it's looking like if I want a supported and trouble-free GPU install, the 580 is the only one because the WX 9100 is half way to a new machine in terms of price.
    --- Post Merged, Apr 22, 2019 ---
    The last issue I ran into was a security update. I'd checked in the Nvidia system pref to see if there was an updated web driver. There was none. I assume this means, well, that there is no newer driver. I go ahead with the security update and have no video. I open my case, remove my 1080 and pop in my old Quadro 4000. Video is fine (hadn't realized I missed a boot screen so much), and I go into Nvidia prefs and check and there's a newer driver that works with the security update.

    I can only assume that the driver check is limited to the exact version of your OS including security updates.

    I hadn't thought to use screensharing, but to be honest, I don't want to have to do that kind of thing on my primary machine. On a machine I'm just experimenting on, I don't care, but this machine is too important to not have proper support on, hence my wanting to switch to a Vega GPU.

    I just need it to work, be powerful enough to work with 4k raw video and be trouble-free. Right now, it's only checking the first two boxes.

    I'll be watching this year's WWDC pretty closely...
    --- Post Merged, Apr 22, 2019 ---
    That sounds like a good option as far as safety, but I just don't want to run on a PSU that I've modded myself. In fact, this thread has made me not want to have a modded PSU unless it had a warranty along with it, which I doubt would ever happen.
  11. CRAYONSEED thread starter macrumors newbie

    Apr 19, 2019
    Thanks! I'll look into the Red Dragon (which incidentally is the name of a camera I shoot on pretty often). If that is relatively simple to get working, it might be the way to go.

    If the Red Dragon is more trouble than I'm willing to take on, I think a new machine is in my future once the now OSX comes out and the software I rely on starts requiring Mojave.

    Also thanks for explaining why it'd be difficult to pre-mod the PSU and send it out.
  12. alchemistics macrumors member


    Dec 27, 2018
  13. CRAYONSEED thread starter macrumors newbie

    Apr 19, 2019
    Almost missed this one. That's an interesting solution for sure, but would result in a power downgrade from what I already have. Looks like there is no perfect solution...

Share This Page

12 April 19, 2019