Cpu vs gpu

Intel Core i7 5820K
3.3GHz (3.6 boost)
6 Cores (12 threads)

VS
GTX 970

witch is strongest, for what, and why?

the GTX 970 is a high end model from nvidia. It’s a little less dollar than the 12 threads 5820K.

Flexibility is where CPU shines. Not speed. For speed the GTX 970 can be quite a few times faster. No real comparison there.

With that CPU you can effectively render scenes up to 64 GB RAM no problem. GTX 970 is limited to 4 GB RAM maximum.

If you compare power draw they are about the same if you don’t OC.

actually they cost the same. thats why i compared those.

not quite

yes if you want the reference aluminium version

Hi, you can use the 970 only for Cycles GPU render, for display a much cheaper card is fine for Blender.
The CPU is involved in all Blender processes, if they multithreaded you get a huge performance boost with a i7 6 core.
For example BVH building, smoke and fire, fluids and much more.

Cheers, mib

by the way mib has anyone done actual benchmarks of lets say calculating the BVH cache with 8 threads vs 16 threads.

My point is that I know some proceses are multithreaded in Blender but you just can’t compare that to the optimizations of Arnold lets say.

plus there are numerous examples of software that make far better use of GPU acceleration than CPU like after effects with OpenCL

they cost the same here where im from… 3700NOK ish…

ah yes aditional taxes I forgot same in my country.

I would expect the gtx 970 to be about 1,5 to 2,5 times faster, depending on the sceene.

ok another question, when i set the viewport to “render”, my GPU is about x2 times faster. but when i actually render it, the CPU is about x4 times faster. why is that? am i using the GPU for rendering wrong?

look under render settings - performance tab. what tile size do you use also what is checked ?

Rule of thumb:
CPU render = small tile sizes = e. g. 32 x 32
GPU render = large tile sizes = e. g. 256 x 256

The Auto Tile Size addon will calculate the best tile size for you, e. g.: You have set your preference for GPU rendering to 256 x 256 tiles and want to render a 1280 x 720 pixel image. Auto Tile size will automatically reduce the tile size to 256 x 240 in order to avoid partial “overhang” tiles to be rendered at the borders.