I use a 7970 for GPU computation. Specifically a project called milkyway@home The application heavily uses double precision floating point operations. Thus the Tahiti's are the best GPUs available to consumers for this particular project. Recently I noticed my 7970 under performing. Specifically, core clock bouncing from 500-1000mhz, voltage dropping from ~1.22v - ~0.9v at the same time, and since it's behaving like that the temps are around 68c while the gpu load says 100%. Usually this project at 99-100% gpu load I'd see over 77c
Serendipitously I needed to work on another machine and I borrowed the monitor from the 7970, shortly after unplugging the monitor I noticed the GPU fans pick up quite a bit. So afterwards I ran GPUz with and without the monitor plugged in or even on. This got me to thinking it was a power-state or power condition, so I went around and disabled or changed all the power settings I could find, windows, Radeon settings, and then I discovered ULPS. I disabled it, I thought I had it but it still performs the same way a few minutes after reconnecting a monitor or refreshing display settings.
The only thing I can think of is a driver change. I recently went through some driver changes on this GPU and hadn't been running the double precision project until recently again and noticed the behavior. I'm trying to find others at milkyway@home to confirm.
Graphics Chipset AMD Radeon R9 200 / HD 7900 Series
System info mostly copied from Radeon settings.
Radeon Software Version 17.1.2
Radeon Settings Version 2016.1121.1657.30480
Driver Packaging Version 16.50.2711-170125a-310869C
2D Driver Version 18.104.22.1683
GPUz reports driver version 21.19.413.0 WHQL (Crimson 17.1.2)
Win 10 64bit i-7 3770k 16gb ram
Other than the double precision performance/behavior the card performs like it should.