Dual Xeon or i7 for VRay RT GPU

[DanielBrew]

Hi,

We will soon be buying new workstations for the 3ds Max + VRay users .The primary motive for buying new machines is that we would like to start using VRay RT GPU for interactive scene development although probably not for final image rendering at this stage.

Our scenes are typically interiors and exteriors of commercial buildings (up to 15 million polys and 400 Mbyte). So on the GPU side we have decided to go for a GTX 680 or GTX 780 to drive the display and one or possibly two Titans for GPU rendering. What we are not quite sure about is whether the base these new workstations around a fast i7 or dual Xeons. I was watching Vlado's presentation at Siggraph this year (here) and from 10:00 he talks about maximising the GPU load by using multithreading on the CPUs. Does this mean that having more CPU cores will be an advantage ie. the dual Xeon system will be better?

Any comments or advice would be very welcome...

Thanks.

[ivaylo.ivanov]

AFAIK, the current CPUs are powerfull enough to feed a couple of high-end GPUs. You may have a CPU bottleneck if you put something like 4x690. Vlado can tell more about such setups, but for a couple of 680/780, a single good CPU should be enough.

[vlado]

An i7 will probably be enough to keep the GPUs busy (and there are ways to control that through the bundle size/samples per pixel). On the other hand, a dual Xeon machine can help with things that the GPU can't handle yet. Also an interesting fact is that with V-Ray 3.0, a good dual CPU machine might get you close to (single) GPU speeds.

Best regards,
Vlado

[DanielBrew]

Thanks for the quick replies.

Also an interesting fact is that with V-Ray 3.0, a good dual CPU machine might get you close to (single) GPU speeds.

Vlado, are you referring to the Embree raycaster speeding up brute force rendering in VRay 3.0? Or are lightcache and IR also quicker in VRay 3.0?

[vlado]

Embree is there but we also ported some of the ideas that we used in V-Ray RT (GPU) to the regular production renderer. They are mostly obvious when using brute force though (either on its own or with the light cache). I haven't looked into the irradiance map although things can probably be improved there too.

Best regards,
Vlado

[DanielBrew]

Exciting news! Another reason to upgrade to 3.0 when it comes out (if we really needed one).

[Neilg]

Also an interesting fact is that with V-Ray 3.0, a good dual CPU machine might get you close to (single) GPU speeds.

I'm legitimately very excited.

Still looking to get it out before the end of the year?

[3LP]

seems so, that's what they said at Siggraph this year when they where showing Beta RT 3.0 for maya

http://www.youtube.com/watch?v=VILKaw317Lo
(End of the video)

Stan