This has been an ongoing issue, but i have tried alot and found something that is reproducable and fixes
the idle clockspeed on the memory being stuck at max of 1250MHz instead of a cool 150MHz.
THE thing that does the trick is following: when i check the windows properties of my monitors it states for all three monitors
they are running at 59 Hz , instead of the usual 60 Hz. When they are at 59 Hz the clock is GUARANTEED STUCK at 1250MHz.
Now i change those refresh frequency settings in windows to 60 Hz , one by one. Nothing happens TILL i set the third and last to 60 Hz
AND SHAZAM. The idle clockspeed immediatly drops down to 150 MHz again....
Back to you AMD engineers.
This fix works every time for me. Tested it with several clean installs in succesion.
works with windows stock 16.6 whql driver, as does with 17.4.1 non whql.