GPU R9 Fury X at +5% OC. max Power Limit (+50%)
CPU i7-4790k at +15% OC
RAM 32GB DDR3
Motherboard Asus Z97 DUAL / Deluxe.
Windows 10 64bit 18.03
Monitor Resolution. 1080p 75Hz FreeSync.
Benchmark result on R9 Fury X.
And running at 4K 60Hz monitor at Ultra, pushing the CPU harder with +20% OC and the R9 Fury X at a +7.5% OC and +50% power limit
There is no DX12 MultiGPU support for this title, I have checked. It will not run in DX12 MultiGPU with a pair of R9 FuryX or R9 FuryX/Nano combination.
So I cannot even get increased FPS that way. Why is DX12 MultiGPU not implemented? I am pretty well convinced a pair of RX Vega 64 Red Dragons would beat an RTX2080Ti in this title if they were run in MultiGPU for example.
Normally at 1080p, an R9 Fury X would perform slightly above an RX580 8GB and it would normally extend that lead at 4K, provided required data can be supplied to the GPU by the 4GB of HBM quickly enough i.e. "there is enough VRAM".
Looking up a performance review for the game here:
Forza Horizon 4 Benchmarked - TechSpot
The RX 580 is performing much better than an R9 Fury X and the RX Vega 64 is perfoming unusually well.
Question is why?
Is it ...
(A). AMD don't bother optimizing the game for R9 Fury X gpus any more and they don't care about them.
(B). The 4GB of HBM is choking performance (I will accept that at argument at 4k, but I think it should be enough at 1080p).
(C). There is some particular feature or improvement in the RX580/GCN 4.0 architecture that is particulary better than R9 Fury X.
(D). The game was coded primarily for XBOX One X Console and that GPU (Scorpio) is mostly Polaris GCN4.0 + "an RX580".
(E). RX580/Vega have better DX12 implementation.
(F). Vega GPU's make use of FP16 (I find this very unlikely since XBOX One X does not support FP16). I think using FP16 on the game would have been announced though.
(G) there is a bug in the R9 Fury X driver.
(H). All of the above.