(Ubuntu/Linux) Change VDC for AMD R9 290 / HD 7950 and reduce temps?

How can I change the VDC for my AMD R9 290 / HD 7950 on Ubuntu/Linux to reduce the temps?

The MSI R9 290 Gaming is currently at 92 C with p0 f100 e900 m1250. My first Sapphire 7950 with VDC 1.09 is at 67 C p20 f80 e1040 m1250 but my second 7950 with VDC 1.25 is at 81 C p20 f80 e1040 m1250.

"atitweak -s" shows 0 VDC for the R9 290. How can I get the info about the current VDC for the R9 290 in the first step and change it in the second step?

The (second) 7950 doesn't change the VDC even if I enter "atitweak --set-core-voltage=1.09 --adapter=1"

atitweak --set-core-voltage=1.09 --adapter=1
Setting performance level 0 on adapter 1: core voltage 1.09VDC
Setting performance level 1 on adapter 1: core voltage 1.09VDC

1. AMD Radeon HD 7900 Series (:0.1)
   engine clock 1040MHz, memory clock 1250MHz, core voltage 1.25VDC, performance level 3, utilization 99%
   fan speed 80% (3631 RPM) (user-defined)
   temperature 81 C
   powertune 20%

Is the "performance level 3" a problem because above it shows "Setting performance level 0 ..."?

P.S. If you have a STILT BIOS please leave a link

Topic: (Ubuntu/Linux) Change VDC for AMD R9 290 / HD 7950 and reduce temps? (Read 525 times)