Gaming with multiple graphics cards is all but dead in 2020, but it shouldn't be. With the few games that support it, the new generation of AMD graphics cards can actually scale very well indeed. In the Vulkan driven Strange Brigade, dual RX 6800 XTs perform at over 190% the power of a single RX 6800 XT, giving near perfect scaling at 4K.
Not quite as strong, but still equally impressive, Tweaktown's results show that those same two cards manage an 80% improvement in Rise of the Tomb Raider, a near-60% boost in Deus Ex Mankind Divided, and over 75% in Sniper Elite 4.
In all of these cases, that puts these two cards well in excess of the performance of an Nvidia RTX 3090, which at $1,500+ is still vastly more expensive than two of those AMD graphics cards. That is, if you can find any of these cards at a viable price.
What's also interesting to take note of, is that the multi-GPU performance is clearly something that has improved with this second generation of RDNA graphics cards. Tweaktown also tested the RX 5700 XT in dual GPU mode but didn't get the same kind of performance improvements. Strange Brigade and Sniper Elite 4 saw big uplifts that neared 100 percent in some cases, but it was closer to 50% in others.
It just seems a shame that so few games support multi-GPUs in 2020. The performance scaling is clearly there, and at those kind of frame rates and memory bandwidth (especially with smart access memory and high-end MD CPUs) stuttering issues should be a thing of the past.
Do you think future games will make use of this feature?