Maybe my question is a frequent, but in fact I didn't get answer listing FAQs here.
So I have new NVIDIA Geforce card where CUDA supported. I enabled Ray-Traced 3d in "composition Settings" Advanced tab and also in fast preview settings. Everything OK and I can see no errors, but when I try to render one of video hive's projects, I see that CPU's load is 95-100% but GPU's is only 0-2%. What is the secret? How to use GPU for project rendering?
There is no secret. CUDA really is only used by the raytracing stuff. If you don't use it, no GPU. Of course there are some plug-ins out there that use CUDA liek GenArts Sapphire and even more use OpenGL, but that is the extent of how, if and when GPU processing comes into play in AE.
The GPU is used very little by After Effects.
See this page for details of what the GPU is used for in After Effects: