Digital Foundry tried out some higher end video cards with the latest Arkham Knight release. The results weren't promising..
Coincidentally I was actually playing Arkham Knight on a 970 last night. That was the card featured for the beginning of this video and again towards the end. The 970 did pretty well in their video holding 60 fps the majority of the time and when it did dip it was typically only to 58-59 fps and only for a couple seconds.
I'm actually getting slightly better results than that. Since SLI support still hasn't been added to the game I deactivate it when I want to play Arkham Knight and set my second 970 as a dedicated Physx card in the settings. With all settings maxed out except for Nvidia's interactive fog I am not seeing nearly as many drops as they even showed in the video for 970 users.
Since Arkham Knight relies so heavily on Nvidia's Physx this actually gives me a pretty big performance gain over anyone who only has one 970. It's still nowhere near as big of a performance gain as actual SLI support would give me but since I am able to hold 60 fps 99% of the time it doesn't bother me that much.
The biggest problem with the game for me is that I have to go into the Nvidia Control Panel every time I want to play it to disable SLI and set the second card to dedicated Physx. When I want to play any other game and take advantage of both of my GPUs I have to go back into the Nvidia Control Panel and enable SLI again. It's a pain in the ass.
If I leave SLI enabled I actually get much worse performance than they showed in the video for 970s. I get drops down to 25 fps in the Batmobile playing that way. This is because the game thinks I have 8GB of VRAM when it looks at both of my cards and even shows that I do in the graphics menu. If you know anything about SLI you know that VRAM isn't doubled because you have two cards. The same info has to be mirrored in the VRAM on both cards so they can each process the graphics. My two 970s in SLI still only gives me 4GB of VRAM but the game thinks I have 8. Supposedly games designed with DirectX 12 support will be able to use all 8GB.
I tested this again last night with SLI enabled and HWInfo running to give me exact stats on what was happening with my hardware while I was playing. HWInfo actually showed that 6.5GB out of 4GB of VRAM was being allocated for use on each card. The game was trying to write 1.5GB more data into VRAM than my GPUs can handle.
Disabling SLI makes the game show the correct 4GB of VRAM in the graphics settings and the game doesn't try to write more than this.
Like the video said, I can vouch that VRAM usage is the major reason for performance drops in this game in my case. HWInfo shows that even on 1 970 running the game my GPU core usage only average 45% on my main card and about 14% on the card dedicated to Physx. Even with this low core usage percentage I still can't play with Nvidia's interactive fog enabled because that causes my VRAM usage to go over 4GB and the game starts to drop major frames when this happens. The graphics settings claim interactive fog only puts me 100MB over my VRAM budget but the game stutters like crazy when it's active.
Even though the game is running well for me you shouldn't have to have a dedicated Physx card or go through this many hoops to get solid performance. You also shouldn't need a 970. Hopefully
yourbeliefs is having a little better luck than the 2GB 960 referenced in this video since he has a 4GB model and VRAM seems to cause a bigger performance hit than processing power for this game.
