Blender 3.2 Performance With AMD Radeon HIP vs. NVIDIA GeForce On Linux
The good news is the AMD HIP back-end for Blender does work much better than the old OpenCL back-end that was dropped in Blender 3.0... The old OpenCL back-end was poorly maintained, often exhibited very poor scaling across GPUs, and just a wreck. Unfortunately, as these Blender 3.2 Linux benchmarks show, NVIDIA with its OptiX back-end was much faster. Even if using the CUDA back-end in some additional tests was still delivering relatively better performance than these RDNA2 graphics cards with HIP.
A look at the GPU power consumption during the BMW scene with the different graphics cards.
Unfortunately the poor HIP performance wasn't limited to just one scene or so but was being consistently showing poor RDNA2 performance against the NVIDIA RTX 30 series on Blender 3.2 atop Ubuntu Linux.
At least for most desktop CPUs, using the Radeon HIP back-end with a higher-end Radeon RX 6700/6800/6900 series graphics card would still deliver faster Blender render performance than using purely CPU-based rendering.