Mkay, thanks for all the help guys. BF4 is now playable and I'm basically satisfied with the Mantle performance I'm getting right now. The hitching still occurs a few times during every match, but everything inbetween those hitches is 100% buttersmooth with an average of 117fps during my last round!
For the people who might stumble upon this with a similar issue and are wondering what I changed/did: I created profiles for both BF4.exe and BF4_x86.exe (just to make sure), disabled crossfire in those profiles (both GPUs will still be used though) and disabled frame pacing (this is probably what fixed it). No more stuttering and the hitching (GPU usage suddenly plummets and you're getting 0fps for a second ro two) has been reduced to a minimum. I also disabled the AMD audio device (I have a TV connected via HDMI) and close the browser window when I start playing. And now I have to atone for my sin of creating a similar thread on the battlelog forums, someone is trying to convince me that Mantle is harmful for my setup because my CPU is "too good" for mantle. Oh well......
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I'm talking about performance and Mantle support. I had to switch back to Windows 7 and everything seems terrible again, at least performance-wise. Even with my i5 4670k overclocked to 4.4GHz I get terrible drops in framerate at certain parts of some maps and whenever "levolution" happens (no matter what graphics settings). Obviously Mantle is supposed to help here, right? Well, the game freezes and stutters every other minute if I use Mantle (no matter if I use one or two GPUs), so that's not really great. Obviously in the test-range everything works beautifully, 100+ FPS across the board and the stuttering when using Mantle also seems to be gone. My questions here are (if you're playing BF4):
Is Mantle working correctly for you? And while we're at it, does Mantle work better in other titles? I've heard people complaining on the BF forums than Mantle works way better in all the other games that have implemented it (I don't own any of them so I can't really test that myself), so it seems to be (again) an issue with BF4 itself and not necessarily Mantle.
Does crossfire/SLI work correctly for you? I seem to get stuttering even on high FPS when using both cards, I don't even know if it is the infamous microstuttering since every other game that supports crossfire doesn't seem to have this problem.
Can you play BF4 under windows 7 without any sudden FPS drops? I mean, it's ridiculous that this game doesn't work correctly with the newest i5 and a pretty decent overclock, I think the CPU resources required are way out of proportion and I still think that this game is an unoptimized mess. With Windows 8.1 and directX 11.2 it works way better from my experience, but that simply isn't an option for me right now and you should never have to switch OS for a game to work correctly.
- "Why aren't you posting this on the battlelog forums?" Because the battlelog forums are basically full of shit and as soon as you try to discuss anything related to performance you get told that your PC is shit or that you have no clue what you're doing. I'm definitely staying away from this toxic environment.
I guess this turned out as more of a rant than anything else, but I'm really curious if I'm missing something really obvious here or if this game is still a steaming pile of shit 1+ years after release. If I can't make this PoS game run well in the next few days I'll probably just uninstall it and, I don't know, play games that are actually good.
Full specs are on my profile, I'm on a completely fresh windows 7 installation using the 14.12 drivers. Every other game works perfectly fine, both GPUs scale really well in most titles and I haven't noticed microstuttering or any of the other crossfire issues (even on heavily Nvidia-optimized games like Metro Last Light).