I have a gtx570 and all the cycles builds (save the old 6.1 build I use) won’t use my graphics card to render. My drivers are upto date and my cuda kernel is supported. I really don’t understand my issue? If you know of any working cycles builds you use or any possible solutions I would be very grateful. Thanks in advance -Jonathan!
You did set your Comute-Device in Blender>UserPreferences>System to CUDA?
I’m having this same issue. Blender 2.64 - Users Prefs-> CUDA enabled, Cycles rendered fine. About 3 - 4 minutes per frame of a trailer I’m working on. Upgrade to 2.65, make sure to set User Prefs->CUDA - now it takers 14 - 20 minutes to render a frame, and also my computer comes to a grinding pace.
So even though CUDA is enabled Blender is using my CPU.