Interesting, as the actual "put code in the mclk and sclk" type stuff in sysfs does NOT actually change the clocks when I tried it on my 4 x R9 290 rig or my mixed R9 280x/HD7850/HD7750 rig.

Did you check /sys/kernel/debug/dri/0/amdgpu_pm_info to see if the clocks actually CHANGED? (change the 0 for the specific card being checked of course).


Might also be a "R9 3xx" vs "R9 2xx" difference, or a GCN 3 vs older GCN versions difference, if it DOES actually work - I only have R9 290/280x + HD 7870/7850/7750 cards to test on while GCN 3 wasn't introduced 'till the R9 285 (Tonga) card.