The issue I'm having with Blender is as follows:

The Cycles Rendering doesn't seem to use the GPU to its maximum power, even though I've read it should to the point where Blender UI becomes unresponsive because of the GPU spending all its power on rendering.

I have the CUDA toolkit installed and tried it with different versions (Newest version and CUDA 4.1). I've even tried the latest Blender version 2.67a and 2.66. No difference there either.

As you can see in the picture blow CUDA is on and I the GPU is selected.

User Preferences

Here are my Render Properties. I've also tried with Feature Set as Experimental, but it showed no changes. All the other settings have pretty much been exactly the same. Apart from the occasional Device switching from GPU to CPU and back again, to see differences. But I'll come back to that below.

Render Properties

Here is the information MSI Afterburner shows me, while I was running the render. Mind you that the scene itself is not complex at all. It's simply the default box, which I duplicated to 4 boxes and they're moving across the scene and go together to form 1 box.

CPU Info

The GPU Usage rarely exceeds 30%. The difference between CPU and GPU rendering is only 10-15 % units.

I'll be editing and adding stuff if I find additional information. It might take a bit of time since I'm trying to solve the problem at the same time.

  • Can you run the Cycles benchmark(…) and post the result and the Afterburner GPU usage? – Mike Pan May 24 '13 at 20:14
  • @MikePan I did the benchmark and it threw up the GPU usage to 99%. Perhaps the problem is just with the scene I used? – Leathe May 24 '13 at 20:20
up vote 13 down vote accepted

GPU usage is highly dependent on the scene complexity. With a very simple scene like the one you tested, it is hard to bog-down a modern GPU. But with a realistically complete scene, you can expect the GPU usage to be a lot higher.

Take a look at this Cycles rendering benchmark

  • @MikePan fyi; see second-to-last paragraph. – wchargin Sep 14 '13 at 23:35

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