MP 7,1 Dual 6900XT from two different card manufacturers?

[Korican100]

I have a Mac Pro 7,1 (Specs in sig)

I just got a 6900xt, I see from a few youtube videos that I should expect some perceivable gains from video editing (fcpx/mac) and gaming (bootcamp/windows11). However; since the 6900xt's can go as low as $500 for open box on ebay, I was thinking about picking up another one.

The one I got is the AMD 6900xt reference card (I believe its called a reference card, its the one made by AMD). My question is, is it ok to mix and match manufacturers? Like have the AMD reference 6900xt, and a Sapphire 6900xt for instance? Or do they both have to be the same make and model kind of deal?

Also, one more question -- leaving the pro vega ii in the machine, would I expect more performance or less? (i dont use thunderbolt displays btw)

Thanks!

 

[Rimmsi]

You can combine different card manufacturers, but you have to pay attention to the length of the card, it must not be more than 310mm, and then non-reference cards have three power connectors.

 

[h9826790]

Despite the cards are from different manufacture, the GPU itself all actually from AMD. This is the key point.

Mixing different manufacture's card usually doesn't matter, as long as they are all from AMD. What worry me a bit is that the Pro Vega II is two generation older. In macOS, this should not be a problem. But in Windows, it's hard to tell. If the Pro Vega II cause any stability issue in Windows, you should able to uninstall its driver in device manager, and change it to basic MS display adaptor. Or even completely disable it.

For FCP, it should able to utilise 2x 6900XT + Pro Vega II simultaneously. However, since the VRAM may be used in mirror mode. Therefore, the 32GB on the Pro Vega II may be wasted a bit.

By considering FCP can utilise uneven GPU quite well, may be you can try connect all monitors to the Pro Vega II. Let it use extra VRAM to handle the monitors. And let the 6900xt only work as a compute GPU to assist the Pro Vega II in FCP.

For crossfire gaming, I can't quite remember if you can mix uneven GPU. Even you can, most likely won't be stable. And in general, 2x 6900XT is powerful enough already. So, for gaming, you better connect the monitor to the 6900XT, and only use 2x 6900XT crossfire. In this case, you should connect all monitors to the main card (once activate crossfire, all output from the 2nd card will be disabled).