iRay CPU + GPU

joseft

Hi All,

i recall reading something a while back about there not being much (if any) benefit to using both CPU and GPU/GPUs with iRay. Something about somtimes actually being slower than just GPU, and also sometimes being unstable.

Is anyone able to confirm this and maybe elaborate a little? i have always had more than one GPU in my machines, so never bothered to try it with CPU and GPU together. I have just built a new machine, and my CPU is much more powerful than my last one, so i figure i might use them together if its worth it

Titan X + Titan X + i7 5930k

Richard Haseltine

Do a test render, but with two TitanX cards I doubt the CPU will add much - as long, of course, as your scenes fit in the GPUs.

LayLo 3D

I have an i7-5960x and 2 GTX 980s. When I include the CPU in the render job, on a render that would take about 6 minutes, it only shaved off 4 seconds... But, used a lot more power and put out a lot more heat. Not to mention, the computer becomes a lot less responsive if I want to do something else while it's rendering. On a side note, adding the CPU with only one GPU alone brought more of a time savings.

My conclusion, it's not worth it to include the CPU.

Havos

I have a GTX 970, a more humble card than others have mentioned above, and I find that render times using the CPU+GPU barely any faster than GPU alone, and is sometimes actually slower. It also makes my PC unusable for other things during rendering, which is why I always render GPU only now.