Comment # 6 on bug 73338 from Nicolas Delvaux

Same problem here on an MSI R7970 Lightning, tested with the latest Mesa
version. Enabling dpm change nothing.

For the record, here is the sensors output when the system is idle:

radeon-pci-0100
Adapter: PCI adapter
temp1:        +33.0°C  

So this indeed seems to just be a fan control issue.