Rendering with the CPU? Why?

Lumani

Honorable
Jun 14, 2013
5
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10,510
I was curious on this topic and I can't find a straight answer on the net.

I consistently see both workstation and gaming cards beating CPUs in rendering test. (Photoshop, 3D/Video rendering)
My questions are: When you render with the GPU, is it the GPU alone? Is the CPU involved? and if it is how much does it effect performance?

I also often see people say things like "If you're doing media or 3D work, then this CPU will work a lot better." without explaining why. :p
Do they say that because they're unaware of using the GPU in that field of work? or because the CPU helps the GPU do a better job than a lesser preforming CPU?

As you can tell I haven't a clue about how the GPU works in this situation and I'd love some help!

Thanks for any info you can provide!