For memory it looks like AMD pushes higher clock speeds at 144hz, setting it to 120hz and it should be back to regular idle speeds. Unknown if it's intended behavior or a workaround for what seems to be some problem with flickering and as a separate issue Vega 64 also had issues with it's lowest memory clock state and crashes but I thought it had been resolved. https://www.reddit.com/r/Amd/comments/8nnuya/psa_vega_black_screen_crashes/ (Not all cards though for this glitch.) I don't believe any of these affects core clock speeds however but I am not 100% sure although the only thing I am aware of is the heightened memory clock speeds at 144hz which goes back to standard levels at 120hz or lower. EDIT: That's a pretty hefty memory overclock too but if it's stable in general then that's not a major concern. I wonder if the GPU hits some spike or throttle for the framerate dips and it scales down as a result of either of these. Still a lot of "ifs" for Vega and what it requires and also a lot of uncertainty on how it scales and what it throttles at. If GPU activity falls below a certain threshold then the card would end up using p5 or lower clock speeds so there's that as well short of registry editing the complete power play table and setting values that way.