Through this mucking around, I determined that the only way to get it to run was to follow WB Games' advice to dedicate one of my GPUs to PhysX to help "performance." It didn't help performance in my experience, but it at least made it so I could play the game. All of my issues, mind you, were with the recommended Nvidia 353.30 GameReady driver that technically supports SLI. More on this later.
Letting the Nvidia driver automatically select the GPU to run PhysX on would cause a crash. And in the bizarre column, depending on which GPU you ran PhysX would limit your SLI support. Run PhysX on GPU number one or two and you get no SLI support whatsoever. Run it on GPU number four and you get SLI or two GPU's only. Running it on GPU number three though, would get you tri-SLI at least, with only occasional crashes to the desktop.
One reliable way I could get the game to run on all four GPUs, at least according to the Nvidia control panel, was to run PhysX on the CPU. But that turned off the game's Interactive Smoke and Paper Debris settings. And as controversial as GameWorks and PhysX are to gamers who run AMD video cards, the effects in Batman: Arkham Knight are beautiful.
It's only after seeing Batman: Arkham Knight with the smoke and paper effects on and off that you realize what you're missing. It's almost enough to make someone who doesn't like proprietary technology forgive the game for using those Nvidia-only features. I mean, that smoke is wondrous. Watch the video and you can see it curl as the Batmobile peels down the street.
The game's performance is another a head-scratcher. Let me remind you, I'm running the game on an 8-core Core-i7 rig with four water-cooled Titan X cards. This rig pushes Middle-earth: Shadow of Mordor, with its HD textures at 4K resolution, at 100 fps. It plays Tomb Raider at 4K on Ultimate at nearly 170 fps. With Batman Arkham Knight, the in-game benchmark reported a dismally low framerate in the 40s. Even crazier, I wasn't seeing any SLI scaling at all. One Titan X, two Titan X, or four didn't move the needle. All of my performance tests were in the mid- to low 40s. I tried the latest GeForce Experience optimizations and multiple reboots with nary any difference.
What's up? I spoke with Nvidia officials who said they're trying to figure out what my problem is, because they are seeing scaling internally. I'll report back once we figure it out.
What about AMD?
Remember, this is the game running on Nvidia hardware, which traditionally has a leg up in performance and stability over AMD GPUs for this franchise. Many AMD users have also reported issues running the game. Even worse, the section of WB Games' FAQ that discusses running the game on both AMD and Nvidia hardware reads like the fine print for a prescription drug that hasn't yet passed FDA trials.
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