Rx480 consumes 20w more power in idle than under Windows

Submitted by Martin

Assigned to Default DRI bug account

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