GPU Confusion

I decided this week that I would like to improve the performance of my PC for rendering in V-Ray, or more probably buy a new one. My current machine is a Dell T1700 with a Xeon E3-1240 3.4Ghz, 24GB RAM and a Quadro K600, so not state of the art. It works perfectly for modelling but rendering is slow.

I’ve been researching GPU rendering but am confused (as is often the case with anything to do with V-Ray) by Chaos Group’s information - they state that GPU rendering is not supported in V-Ray on the same help page that tells you how to set the RT Engine to GPU!

If I were to invest in a new machine, probably with dual GeForce cards rather than a Quadro, would I see a significant performance increase?

I’m not an expert in that subject but what I know is:
Vray supports two independent rendering modes, the traditional CPU rendering mode, CPU intensive with is named Production Render and it never uses the GPU. And RT Render (Real Time) which can use the CPU or the GPU either with OpenCL or CUDA engines.
RT is very fast to render, but it isn’t the same as doing a production render (yet).
My workstation is very similar to yours Dell T1600, Xeon E3-1270 3.4Ghz 16Gb RAM and a Quadro 600. And my experience with RT is that if I use the CPU mode I can get similar results to production render fast, with some illumination differences and less contrast. In any of the GPU modes it doesn’t render displacement maps, and I don’t see any significant performance improvements. Maybe a more recent card would yield better results, but I can’t tell.

Thanks for your reply, Filipe.

I have read about the differences between the production renderer and the RT Engine within V-Ray. Until recently I always used the production renderer but have started to experiment with RT, mainly in the hope of a performance increase. However, the Chaos Group help pages for VfR does specifically state that “V-Ray RT in Rhino does not currently support rendering on the GPU”. This tallies with my experience this week trying the different modes, i.e. CPU or CUDA. I don’t notice any difference. Perhaps, as you suggest, this is due to my card being a low end Quadro. I’d like to know for sure that a better card (or machine) will actually improve performance.

Thanks again for your input.

This might help:
http://forums.cgarchitect.com/75337-3ds-max-gpu-impact-rendering-gpu-vs-cpu.html

Thanks again, Filipe. That link looks very helpful. I’ve read the first page and there’s a lot to take in but it looks like very useful information.