On github Valve employee was denying bug, telling people that it’s only bug in performance overlay (like it simply slow to draw frequencies in between 200-1040) but was proven wrong in the same bug report thread. Demonstration of this bug presented here.
I just tested it myself and you still get major performance issues with gpu set to auto. “Allow tearing” setting has no effect on this. Even if game can go above 1040 mhz by itself it drop frequencies and frames hard on auto because occasionally it switches to 200 mhz or 1040 in scenes where it should not do that.For example Code Vein is not able to hold stable 60 FPS but able to hold stable 50, with locked GPU you will get flat line on frame time graph. With auto you will get major dips.
I guess we’re stuck with “unstable” stable OS 3.5.5 - 3.5.7 for a while because holidays starting in US.
On steamOS 3.5.5 LCD model, this bug occurred notably in games like Darksiders 3, sniper elite 4, Shadow of War, deus ex mankind divided - as well as the steam Home Screen. It caused severe stutters/frame pacing issues and audio crackling.
Surprising, the bug did NOT occur in Darksiders Warmastered edition for me - the gpu could automatically scale to any frequency in this game. I wonder why.
I quickly reverted to steamOS 3.4.11 and everything seems to be normal now. No performance issues.
I feel that they might have pushed the 3.5.5 update just to get the OLED versions running. I wonder if the GPU lock was a way for valve to push OLED battery life - but that’s just a speculation.