Blender version 2.93.3 GPU: GTX 3080 RAM: 32 GBS CPU 9700k Rendering in Optix+Motion blur on causes the error "Failed to build OptiX acceleration structure" and "System is out of GPU memory." Turning off motion blur fixes this problem.
Also Cuda+motion blur on seems to be working just fine.
I'm not sure why motion blur is causing this memory issue. I've tried to restart blender and the problem remains. It'll be the first time using motion blur so maybe I don't understand how some obvious setting could break it. Update: I figured out that the problem seems to be having Particle systems enabled. I'm not exactly sure why but when I turn off the hair to my character it works.