Rx480 consumes 20w more power in idle than under Windows

Submitted by Martin

Assigned to Default DRI bug account

Link to original bug (#110865)

Description

Created attachment 144485
logfiles as requested in the amd bugreport guide

First I am not sure where to file that bug, so please be gentle with me, if I selected the wrong component.

I noticed for a while higher temperatures of my Videocard when my pc was just idling with gnome. Then I dug deeper and found out that my "zero fan" videocard does not stop the fan when I run Linux.

So I ran this line here:
watch -n 0.5 cat /sys/kernel/debug/dri/0/amdgpu_pm_info
and it showed me that the MCLK does not clock down to 300MHz as it does with Windows 10.
GFX Clocks and Power:
2000 MHz (MCLK)
300 MHz (SCLK)
300 MHz (PSTATE_SCLK)
300 MHz (PSTATE_MCLK)
1000 mV (VDDGFX)
24.75 W (average GPU)

GPU Temperature: 45 C
GPU Load: 0 %

I have a multimonitor setup with two 1920x1200 pixel screens. When I use Windows 10, the MCLK does not go beyond 300MHz when the desktop is idling. (measured with hwmonitor)
When I power-off one screen under linux the (average GPU) goes down to 8-10W and the MCLK drops to 300MHz, so the card can clock down, but is somehow prohibited by the driver or configuration?

I followed this bug report guide from amd:
https://www.amd.com/en/support/kb/faq/amdgpu-installation#faq-Reporting-Bugs
and attached several logfiles.

Attachment 144485, "logfiles as requested in the amd bugreport guide":
logs.log