I did get Unigine Heaven running with DPM on for a few seconds (before
hanging), showing way better frame rates than before.
It really seems that
- The performance issues are most likely caused by the lack of DPM
- DPM for Grenada GPUs is not supported completely
Or:
- My card has a really weird (stock) VBIOS that Radeon(si?) cannot
interpret/work with.