Cant Change power profile ubuntu 15.04

Question

I was using following command to change graphics card power profile in Ubuntu 14.10 got from Radeon HD 6950 temperature is way too hot.

echo low > /sys/class/drm/card0/device/power_profile

But after installing 15.04 the command failed and error is

# echo low > /sys/class/drm/card0/device/power_profile
bash: echo: write error: Invalid argument

• no proprietary drivers installed

How can i change the power profile.

Thanks

Vishnu V

Answer 1

I'm guessing this is a permission issue. Try running the command as sudo:

sudo echo low > /sys/class/drm/card0/device/power_profile

Or change the permissions on the power_profile file allowing people to write to this file.