MP 7,1 Multiple AMD GPU Question

[Stairway]

I'm currently using a single PC reference 6900XT card in my Mac Pro 7,1, and have been thinking about addding a second one. If I do this, will the system recognize and be able to use both cards, or is there a special connector needed (like the infinity link connector used on the Duo MPX modules)?

Thanks in advance.

 

[mattspace]

I'm currently using a single PC reference 6900XT card in my Mac Pro 7,1, and have been thinking about addding a second one. If I do this, will the system recognize and be able to use both cards, or is there a special connector needed (like the infinity link connector used on the Duo MPX modules)?

Thanks in advance.

The W5700X MPX GPUs don't have the Infinity Link option, but the system sees and uses both of them (or at least I can see in activity monitor that tasks get sent to the other card at times), though it will usually run stuff on the display card.

 

[Stairway]

Thanks for the response; I think I'll give it a shot, and report back. I've been really happy with the RX 6900XT performance, so I figure doubling-up could be worth it.

 

[mattspace]

Thanks for the response; I think I'll give it a shot, and report back. I've been really happy with the RX 6900XT performance, so I figure doubling-up could be worth it.

I would imagine it's going to be idle (but eating power) most of the time, unless you have an app that specifically maxes multiple GPUs.

 

[vslab]

It is possible, you just need the additional pci-e aux power cables for the Mac Pro 2019, these mini plugs that you also used for your first XT I guess. As per specs those aux power ports are able to deliver 150 watts each. For a 6900 you would need the two of them = 300 watts plus the pci-e power delivery of 75 watts and you get 375 watts from that configuration and you should be safe. I have tested this configuration and it runs flawlessl. I wonder if it is possible to make or buy a connector that is pulling power from the MPX power delivery on slots 1 and 3. If that was the case one could even employ 3 or maybe even 4 6900 cards. But I haven’t found any build with such a connector (MPX to 8-pin) anywhere.
But one more thing about the 6900 card. The same card gives me about 40% more performance when being used on windows 10 In bootcamp. That’s the drawback with the Mac OS I find.

 

[Stairway]

Thanks everyone; I did it. Both cards are recognized and working in both macOS and Windows.