Oh hai again!
Powertune set too low.
Clockspeeds/Voltage set too high
>>> Faulty PSU
Faulty graphics card.
I actually run the 7850 in my HTPC at 725/1000 instead of the 860/1200 it comes at because clock x voltage = heat, and I want my fans to run queitly even under load.
At stock speeds, raising powertune should do nothing, because the GPU should be able to run at 100% load without exceeding it's stock power budget anyway.
Lowering powertune limits results in rapid dithering between 100% state and the first power-saving state. There are going to be a few of these depending on how the BIOS is set up but as an example it'll look something like this:
- S1 - 860/1200, 1.15v
- S2 - 600/1200, 1.09v
- S3 - 450/800, 1.02v
- S4 - 150/300, 0.93v
Each state has a different power draw and if it's not getting enough power (or if the power draw exceeds the powertune limit) it will briefly drop down to a lower state before clocking back up to the previous state.
A GPU-Z graph of this behaviour looks "furry" with the state changing hundreds of times a minute.