I recently installed a Sapphire Pulse Radeon Rx580 8gb on my 2010 era (with upgraded CPU) Mac Pro tower. I did this because my former GPU, a NVIDIA GTX 970 is not "Metal Compatible" and would not allow me to upgrade to Mojave. I selected this GPU because it was one of the few recommended GPU for Mac Pros. I use blender a lot, and was hoping that I would get something of a boost in performance from the upgrade.
Alas, no dice. In fact, the GPU is even slower than the CPU when rendering benchmarks like "Classroom" or "BMW". With my GTX 970, I got a good boost, with benchmark times sometimes as much as 3x faster.
I'm beginning to regret the "upgrade". I don't need amazing performance, just something that makes cycles run quicker.
Am I doing anything wrong? Is there any patch or fix that I can download that will help?