I have a prob, with GPU rendering, i was rendering with GPU like yesterday, but all of a sudden it switched to CPU and when i go to Us Pref/System there is no selection between GPU CPU there’s only CPU. I have all Drivers up to date. Plus i have 650 GTX with all supports needed 4 GPU rendering ( in nutshell it was rendering with GPU perfectly las night). . . PLS HELP AS FAST AS POSSIBLE!!!