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Doom Vulkan - Enhanced Sync Stuttering with RX560

Question asked by dave_g on Sep 17, 2018
Latest reply on Sep 18, 2018 by dave_g

I've tried several variants of Adrenaline drivers in order to get a decent Doom experience on a RX560 on Vulkan, up to the latest optional release. The problem with the game's built-in vsync is that it will vary wildly whenever it goes below 60, bounce from 30-60 and significant stuttering. No-vsync is an option of course, but I also hate tearing. So Enhanced Sync would seem to be ideal. However, in practice...


The problem is that whenever it's enabled, I get massive stuttering above 60fps, and while the drops below are far smaller than with vsync according to Doom's frame rate statistics, it certainly never feels like a smooth experience regardless of the FPS. Also, I never notice any tearing - which according to the explanation of Enhanced Vsync, I should see when it dips below 60. I just get a constant stutter. Note this is not unique to Doom with Enhanced Sync (I find it stutters frequently in other games too, Doom is just where I need it most), it's just never lived up to its promise for me.

Frame Rate Target Control (FRTC): If I force this to 60 along with turning on ES, then the stuttering above 60 is gone - for a bit. The problem is that the CPU spikes above 16.7 ms are frequent, with just Enhanced Sync and FRTC not enabled my CPU (Pentium G4560, low-end I know but not a bottleneck for Doom) usually stays under 10ms according to Doom's graphs. With FRTC enabled though, I see constant GPU spikes of 60ms+ every few seconds, every few seconds you get a momentary frame-rate "skip" where it seems to jump several frames at once regardless of the activity on-screen.


The only way to get a reliable 60fps without stuttering is to just leave vsync off and use FRTC to lock to 60, but that means even at a perfect 60 I still get this slow-moving tear line across the screen as I pan around. It's the best option so far, but really Enhanced Sync should not be behaving as it is as is my understanding of it.


Anyone else?