that might also be some problem with the benchmark.
No but that ran fine with radeon driver.
yes, but it might have issues when using amdgpu. After all, your cards only have experimental amdgpu-support which means that some issues might occur. Those issues might disappear later on with future updates both on the system side (drivers in Kernel and Mesa) as well as with future updates of programs (games and benchmarks)
Cards with full amdgpu support don’t need those boot parameters to use amdgpu.
OK Then unfortunately I have to live with it 