I have two GTX 1080 and for a while when i press F12 blender rendered everything with 2 tiles. Right now no matter what i do there is only one render tile. In system tab in user preferences i can ether select both GPUs or none, does anyone know a solution to this. BTW it is not hardware
Someone answered me elsewere.
Turns out you need to have your SLI "DISABLED" which is very confusing since you need to enable that to have better performance in everything else.