IRAY not fully using GPU?

onyxlee_9b3cce7f35

Hi guys, I am quite sure that in my device settings, I chose both my GPU and CPU, but during the rendering, CPU stays 100%, GPU is minimal. It went to 40% for a couple of minutes, then came back to 3-4%. Is that normal?

Thanks.

JVRenderer

Try checking GPU only instead of both GPU and CPU

jbdiminnie

Looks like scene is requiring more than your 6 GB of GPU VRAM causing it to drop to the CPU.  You can change the "copy" graph to "CUDA" which will show if your GPU CUDA cores are being used--if they show 0% then the render ran out of video memory and resorted to CPU render which is much slower.  You either can use a tool to reduce texture sizes to conserve VRAM or try rendering the scene in parts and then stitching them back together using GIMP or Photoshop, etc.

onyxlee_9b3cce7f35

Thanks. I just found out that by default, the task manager doesn't show the CUDA performance.

Here is how to show it. Once you switch it on, it will show you actually both GPU and CPU are rendering full throttle.

jbdiminnie

You may want to disable CPU rendering, since you are running a RTX card.  Running with both GPU and CPU may actually slow down your render times since the system will try and render frames on both simultaneously--since your GPU is faster than the CPU, this will cause a delay in rendering frames (there is a limit where the system stops waiting for the CPU if it is too slow to render but there is still a wait time), increasing your total render time.

onyxlee_9b3cce7f35

Thank you. Your concern seems legit. Although I have been using the default setting (CPU+GPU) for a while, I did run a test and found out that, if I am only rendering one frame, CPU+GPU vs GPU only are not that far apart, simply because CPU's capability is almost neglectable. CPU+GPU is probably 1% faster than GPU only, in my single frame test. Maybe rendering animations will be a different case.