A little backstory using the 15.11 Crimson driver:
About a month ago when playing games my GPU decides that it wants to down clock to half speed performing in the 500-700mhz range despite being around 40C in temperature. When I noticed it, I was playing GTA V at 4k resolution. The lags and stutters would happen for extended periods of time. There is no reason why the card should think it needs to save power or preserve itself from damage. I am using no other GPU software other than AMD drivers. I have tried changing both GTA and global game settings in crimson but nothing seemed to correct this.
I uninstalled and went back to the 15.11-Catalyst drivers and they work fine without any issues. The card runs at 1050mhz when I am playing games and never goes lower.
I saw that the 16.1-Crimson drivers came out and figured I'd give them a try. The lags and stutters have only gotten worse since 15.11-Crimson. I cant even watch netflix on firefox without stutters. I tried the 3rd party Clockblock program as others have said but it didn't fix the issues for me. I again uninstalled and went back to 15.11-Catalyst drivers and the problems went away. From what I have researched it has something to do with a power saving feature in the new drivers. Any help or insight would be great.
AMD Sapphire R9 Fury X (Stock clocks)AMD Phenom II X6 1075T (OC @ 3.5Ghz, turbo disabled) - Corsair H100 Cooler
Crucial Ballistix Tactical Tracer DDR3-1600 4x4GB
OS Drive: Samsung 830 SSD
Other Disk Drives
Windows 7 x64