5,1 No Dual GPU Support in Mojave?

Discussion in 'Mac Pro' started by z3thon, Oct 11, 2018.

  1. z3thon, Oct 11, 2018
    Last edited: Oct 11, 2018

    z3thon macrumors newbie

    Joined:
    Dec 1, 2017
    #1
    Hey everybody! So my move to Mojave has been quite the experience. Let me explain my use scenario.

    Before Mojave I had the following setup:
    GT120 + RX580

    This allowed me to access my boot screen on a separate monitor and my RX580 would run my 2K monitors. Everything worked like a dream and I very very often need to boot into different OS's. The Boot Screen selector was a daily use for me.

    The thread(s) here1 here2 explaining other methods of booting without using an EFI compatible card has not resolved my issues so I decided to upgrade the GT120 to the GT640 which is an EFI + Metal compatible card that would give me the same use scenario back as before. Access to the boot screen on a secondary display.

    I installed the GT640 got access to my boot screen again (hell yeah) and then fired up macOS. Once I got to the login screen all the monitors connected to my RX580 didn't have a picture. They had (and still have) a backlight just showing a black screen and in the OS are taking up real space. I can send my mouse into the other screens, see them in the System Preferences screens section and I can screen share into my desktop from my laptop and see that all the screens exist. BUT the monitors don't display the screen's image.

    I have tweaked and played with every option I can think of. When I take the GT640 out and boot again all the monitors connected to my RX580 work no problem (but I lose my boot screen). Pop the GT640 back in with the RX580 and the screens connected to the RX580 play hide and go seek on me again.

    Even more interesting is this: I booted into Windows (from my newly found boot screen using the GT640!! :D) and the two monitors connected to the RX580 were also inactive. So I went and downloaded AMD's drivers and installed them. Boom instantly all 3 screens now came to life. All the screens connected to the GT640 and the RX580 work perfectly in Windows now. Before installing the drivers I cannot remember if the screen space actually existed or not, I don't think it did, but once I installed the drivers everything worked great!

    Apple makes the drivers for the Mac, there are no downloadable AMD drivers so I am posting this issue here to see if there is some kind of resolution in the works or if anybody running 10.14.1 can try this dual GPU set-up out and let me know if it works in the next update of the OS (which would be amazing.)

    If anybody else find this odd and want's to reach out to me directly. I've got this posted on the MacProUpgrade FB channel as well. I honestly cannot figure out how to resolve this issue and it's driving me crazy.

    Any help would be appreciated.
     
  2. z3thon, Oct 11, 2018
    Last edited: Oct 11, 2018

    z3thon thread starter macrumors newbie

    Joined:
    Dec 1, 2017
    #2
    My Bug submission to Apple. Let's hope they decide to do something for this!!

    Area:
    Graphics & Imaging

    Summary: My previous setup on High Sierra was GT120 + RX580. The GT120 was connect to a secondary monitor that let me view my boot screen and then the RX580 was powering my dual 1440p monitors.

    With the GT120 becoming a paperweight since Mojave doesn't boot while there are any non-metal compatible cards installed in the system I upgraded my GT120 to the GT640 which has the Mac Pro's EFI support + Metal support. Theoretically this would solve my problem and give me access to the boot screen again. Result: It did! I could access my boot screen again and choose which OS I am booting into by holding down the Option key at boot.

    Hiccup: Once I booted into MacOS Mojave I realized all the monitors connected to my RX580 were staying blank. Like black but with the backlight on. The screen connected to my GT640 works just fine but I lost operation of the other two connected to the RX580. If I pull the GT640 out and boot into Mojave with just the RX580 installed I get picture back on both 1440p screens but I lose my ability to see the boot screen from the EFI supported GT640.

    The system recognizes the hardware and even knows that the screens are connected to the RX580. In fact the screen real estate is technically still there too! My mouse can zoom off the screen into the other two monitor's black abyss. If I remote into my computer from my laptop 3 screens appear as active and I can see my mouse moving around on the other two screens but the monitors themselves never show any picture or display this.

    Booting into Windows I initially had the same problem until I installed AMDs drivers and then immediately all 3 screens came to life (1 connected to the GT640 and 2 connected to the RX580.) So this must be an issue within macOS Mojave and it's capacity to use dual GPUs both connected to the Mac Pro's motherboard PCIe sockets.

    I have not tried any other dual GPU configurations since graphics cards are not cheap but I would daresay that this issue is consistent in Mojave where Dual GPU setups will only support 1 GPU.

    Steps to Reproduce: Connect two Metal compatible GPUs to a 5,1 Mac Pro. 1 GPU must have EFI support (allowing you to access the boot screen.)

    Expected Results: The card without EFI support will not provide picture to the monitors attached (regardless of their resolution or monitor type)

    Actual Results: The monitors attached to the card without EFI support (but with metal support) stay blank with the backlight on. Multiple displays tested no resolution works.

    Version/Build:
    macOS 10.14 (18A391)
    Darwin 18.0.0
    Boot Mode: Normal
    Secure Virtual Memory: Enabled
    System Integrity Protection: Enabled

    Configuration:
    Mac Pro 5,1
    Dual X5690 @ 3.46GHz
    64GB 1333MHz ECC DDR3
    Nvidia GeForce GT640 1024MB + Radion RX580 8192MB
     
  3. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #3
    GT460? It's a Fermi card and do not have Metal. Maybe you want to write GT640, Kepler Metal card?
     
  4. z3thon thread starter macrumors newbie

    Joined:
    Dec 1, 2017
    #4
    Yeah, I actually just realized my typo, resubmitting my bug report.... >_<"
     
  5. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #5
    Did you ever receive a reply from apple for your bug report? I have a new Sapphire RX 580 installed and a non-mac EFI GT 640 installed in my 5,1 and can report the exact same behavior under Mojave 10.14.1

    I can see the card and the monitor in System Information as well as interact with the dock (launched SIRI) on the darkened screen. As far as the OS is concerned the desktop is there and active I just cant's see anything on the one monitor hooked up to the RX 580 through DP.

    I miss my dual-card/dual-screens
     
  6. orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #6
    i cant see apple seeing any problem with that, they only support :)rolleyes:) the RX 580 and it's acting correctly the way he described so for them thats fine.
    the GT640 has no support from apple, apple never told anyone that it will work.
    (it must be a flashed GT640? to get boot display and thats not supported by apple contact the seller)

    so as apple's only just supporting the RX580 i cant see them helping anyone with a NVIDIA card
     
  7. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #7
    I believe that the original poster has a flashed card and thus a boot screen - I do not - I was just hoping to find a blade replacement for my GT 120 paperweight now that I have committed to Mojave.

    I do find the behavior difficult to explain in anyway that I understand - working desktop space but blacked out??

    Has anyone gotten Dual GPU functioning in the MP5,1 under Mojave?
     
  8. orph, Nov 2, 2018
    Last edited: Nov 2, 2018

    orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #8
    it works but there's always been problems with some cards, on 10.13 it's easy on 10.14 apple has drooped support for a lot of older cards.
    look at there new graphics stuff there's been lots of talk about it.

    there's always been bugs with not official supported cards, my GTX 660 & 770 had a bunch of bugs i found over the years with osx10.8-osx10.13 from app crashes hard crashes and both apple and nvidia drivers so it's not a huge surprise.

    im going to assume it's to do with how apple's treating gpu's support levels

    anyway im sure something like a RX 560 & RX 580 will be relay happy both installed with 10.14

    PS there are a bunch of apple that support dual GPU, like FCX so it is supported
    edit tho to be fair im the 5.1 is super super super old, way past it's life time so any support apple gives is to my amazement
     
  9. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #9
    If you like strange then there is this - I just took a screenshot of the two desktops and the black screen is indeed a working functioning desktop in the OS. I created a Stickie and drug it onto the darkened screen prior to the screen shots.

    The stickie is where I placed it from the drag as is the typical desktop.

    If anyone can think of something that is going on here that I could correct to get both cards displaying correctly I would appreciate it ... I can't even think of a good place to start on this?

    Screen Shot 2018-11-02 at 8.42.24 PM.png Screen Shot 2018-11-02 at 8.42.24 PM (2).jpg
     
  10. orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #10
    have you done any trouble shooting?
    if you only have two displays why do you need two GPU's?
     
  11. KXB17 macrumors newbie

    Joined:
    Jul 10, 2018
    Location:
    Maitland, NSW, Australia
    #11
    Obviously reading more than the title was a bit much for you, so here's the answer in bold. I can understand this being easy to miss since OP buried it in the fourth line of the post. Hope this helps.

    #1
    Hey everybody! So my move to Mojave has been quite the experience. Let me explain my use scenario.

    Before Mojave I had the following setup:
    GT120 + RX580

    This allowed me to access my boot screen on a separate monitor and my RX580 would run my 2K monitors. Everything worked like a dream and I very very often need to boot into different OS's. The Boot Screen selector was a daily use for me.
     
  12. orph, Nov 3, 2018
    Last edited: Nov 3, 2018

    orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #12

    @KXB17 is MarkSt using 2K displays if so i missed it, he's not the original thread starter just some one who found an old topic and was checking to see what was his problem.

    i was asking if he had done any trouble shooting,

    was not shore how far he had gone, what display cable kind (DP has some bugs when display is set to wrong settings), swapping cables, changing video card and seeing if both displays can be powered by just one GPU

    edit
    try to be polite i was trying to help and if i have missed something you can point it out and help MarkSt who has an actual problem so support him instead of pointing out my mistakes.
     
  13. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #13
    As for your first question of why - I think that the thread starter has specific reasons as to why he uses 2 GPUs - I have been running my system with a GTX 970 and my GT 120 fo quite awhile and I have gotten used to using one monitor for more graphics intense items (gaming often) and the other for streaming from the web without having much of an impact on performance of either. Since I have switched to Mojave and have only been using one GPU (RX 580) I have found a decrease in performance and responsiveness vs dual GPUs.

    That aside - I am also just genuinely curious about things that don't make a lot of sense to how I understand them to be operating :)

    Second question: I have done some trouble shooting but I'm having a little trouble figuring what to do next when everything I can see within the system suggests that the RX 580 is operating as expected except outputting video to the screen.
    1. I have set active desktop to the RX 580 monitor and had the Menu Bar switch to the dark screen.
    2. I have then powered off the RX 580 monitor and had the expected result of having active desktop and icons switch to the second monitor.
    3. I have played with various digital cabling: Display Port | HDMI | DVI-D on both cards various combinations with no change to the dark screen other than the moving of active desktop when one card was not connected to a screen.
    4. I even ran a test with GFXBench Metal with results showing up for both cards even though the RX 580 screen remained dark throughout.
    I have now pulled the GT 640 back out and am running off the the single card with all things acting normal. I would love suggestions or reports of others who have multiple GPUs running in Mojave. So far searching the boards I have not come up with much on this.

    I think my end game is to have the GT 640 flashed with a Mac EFI so that it will become a straight replacement to the GT 120 that no longer works under Metal. But this won't matter if I can't find evidence of Multi GPU function in Mojave
     
  14. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #14
    Here are some screen shots from today and last night - not sure what to block out exactly to protect from posting so if I overdid it sorry - If I left something exposed that I shouldn't have please let me know.

    Pics from today are with just the RX 580 installed supporting both of my monitors. Those from yesterday show both cards installed with the dark screen problem
    Screen Shot 2018-11-02 at 8.34.28 PM.png Screen Shot 2018-11-02 at 8.34.57 PM.png Screen Shot 2018-11-02 at 8.34.49 PM.png Screen Shot 2018-11-02 at 8.34.40 PM.png Screen Shot 2018-11-03 at 11.28.56 AM.png Screen Shot 2018-11-03 at 11.32.06 AM.png
     
  15. orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #15
    it's worth just testing with one GPU, iv got an RX 580 and have no problems with 2-3 displays with a lot of different tasks from video editing to playing a game and watching a video online or playing back two 4K youtube videos one on each display (my internet is not up to 3 4K videos streamed at once)

    from my understanding everything will be rendered on the main card and the second card is just ruining out puting to the display, at least it used to be so it may have changed.

    it was/is only when apps that have been programed specially to use dual GPU's was there any real use of the second GPU (and used to work best with matched cards)

    but it's not something im an expert on, maybe some one with better knowledge will be able to answer.

    there have been problems in the past using DP and the display set to the wrong setting so may be something odd like that too

    ps at least you can use just the RX 580 to drive both displays until there is a better answer.
    may have to wait for the new NVIDIA drivers or have a newer second card with the same metal support level or idk rly just guessing (may even just be a bug in osx10.14 which will be patched by 10.14.3 etc)
     
  16. MarkSt macrumors newbie

    MarkSt

    Joined:
    Nov 2, 2018
    Location:
    Seattle
    #16
    orph I appreciate the thoughts - I am also hardly what I should call suffering since I have such a well supported out of the box card available to run both monitors :)

    I was unaware of the behavior that you described where GPU tasks are rendered on a single card and then the display task being handed off to the second card ... If this is the behavior that is going on here then perhaps all the video is being processed on the GT 640 when both cards are present and the display handoff to the RX 580 is causing the issues??

    To test this - is there a way to effect the load process or perhaps the bus placement to force the RX 580 card to handle graphics processing and then hand off display to GT 640?

    This would make much more sense as to how I would expect the OS to select things anyways - both because of the placement of both cards on slot 1 and 3 as well as the GPU capabilities between the two cards.
    Slot1 > Slot3 + RX 580 > GT 640

    Can you point me towards someplace to research this behavior on earlier OS's - I hope to learn enough to at least formulate some decent questions that I can test out?
     
  17. orph macrumors 68000

    orph

    Joined:
    Dec 12, 2005
    Location:
    UK
    #17
    well im not up on this, i know about dual GPU's and how they work with say resolve or FCX and i know how they work on windows.

    im not relay up on how they work in osx in the way you described (ie dont know 100%)
    but im fairly sure it used to be just main card did work secondary card just displayed the frames which is the same as windows it used to be that only app's specially coded to use dual cards where able to do it. (not a lot)

    if you relay want help may be worth doing a new topic asking how dual cards work in osx 10.14

    from my point of view the GT 640 will be about 5%-10% of the speed of an rx 580 so not worth it even if it did do something.

    or just go back to osx10.13
    --- Post Merged, Nov 4, 2018 ---
    on a side note in windows the OS or general apps do not use dual GPU's at all.
    GPU A will do all the work (well all the real work)
    GPU B will only drive a display (IE no work at all done on the card)

    only games or a few apps can "see/use" dual gpu's and with games it has to be matched GPU's and bugy at best at worse dose not do anything :D
     

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