Back in august, when AMD launched its Radeon RX Vega graphics card, it was not yet possible to combine multiple cards in a CrossFire configuration. About a month later, a driver patch came which included the multi-GPU support. Due to many big releases in the last couple of months, we did not have much time take a closer look at this, so we shall rectify this now.
In the presentation AMD gave to the international hardware press prior to the Vega-release, the word CrossFire was not mentioned once. At the launch of the RX 480 and later the RX 580 AMD hinted at performance expected out of two cards, but they have not yet launched their top of the line GPUs, so the hints have gone mostly unnoticed.
When Vega finally came out, it was not yet possible to use multiples of it, until the Crimson ReLive 17.9.2 driver version was released as well. The driver made it possible to use a maximum of two GPUs, triple and quad CrossFire(X) seems to be a thing of the past. In this, AMD follow Nvidia who also stopped supporting more than the double GPU setup since their Pascal generation.
The reason why GPU designers no longer focus on CrossFire and SLI should be clear. The promise of DirectX 12 was that scaling across multiple GPUs would be much better because responsibility for implementation shifted from the driver to the game developer. In practice, none of the developers, except a few such as Nixxes (Rise of the Tomb Raider), seem to spend any time working with multi-GPU configurations and so virtually all DX12 games have so far done nothing with a second video card.
For this test, we specifically went in search of games scaled with CrossFire; the number of games in our standard test suite that did not do so has grown so large that it would not be worth the time to test all those games in vain. From the standard game selection, we use GTA V (DX11) and Rise of the Tomb Raider (DX12). We also take Battlefield 1 with us, which has recently been providing support for DirectX 12 multi-GPU. We also tested with Ghost Recon Wildlands and Project Cars 2. CrossFire should work in the latter game, but with two Vegas we did not get them to work in sync.
The other games you're used to see in our tests (Doom, Hitman, Rainbow Six Siege and Total War War Warhammer) don't support CrossFire. In any case, games with good CrossFire support seem to almost be as rare as unicorns. We have lost count of times we had to write that multi-GPU didn't work or didn't work properly in our reviews the past year.
For the benchmarks, we use a test system with the following specifications:
- Intel Core i9 7900X Skylake-X 10-core CPU @ 4.5 GHz
- ASUS Strix X299-E Gaming motherboard
- G.Skill Trident Z 32 GB DDR4-3200 CL14 RAM
- 2x Samsung 840 Evo 1 TB SSD
- Windows 10 x64 Creators Update