By this point, I was hoping that one little driver toggle fix would solve the performance issues throughout our benchmark suite. Unfortunately, the taxing Metro: Last Light benchmark shows that there are still issues to be worked out. FCAT indicates 49 average frames per second, Fraps confirms, and our original quad-CrossFire piece also reported 49 FPS.
Frame rate over time makes it pretty clear that there’s some sort of bottleneck in the Metro benchmark. Thinking this might be limited to the canned test, we played through pieces of the actual game and found that performance didn’t improve there, either.
There’s clearly a bottleneck of some sort in play, and given the close proximity of four different configurations, it might not be an AMD-only problem. With that said, AMD didn’t have any feedback regarding what might be happening when we asked.
The frame time variance figures show only that two Radeon R9 295X2s land at the back of the pile. A 5 ms worst-case figure shouldn’t be construed as bad, though. Moreover, our experiences in-game and with the built-in benchmark didn’t turn up issues with stuttering.
Quad-CrossFire does demonstrate the large variance spikes, though again, the experience isn’t made perceptibly worse by them.