What exactly does this do?
Logically, the rendering is done via software running on the hardware, so what does this setting do?
I would assume hardware would be the option you want if you have an amazing GPU, but doesn't the rendering get done on it anyways since the software (presumbly) uses the GPU?
Or does it normally use the CPU, and the hardware setting uses the GPU? Are there any bugs or other info I should know relating to this?