GPU not showing up (Blender 2.78c, 2x gtx 970)

I’ve just finished a project and was starting to play around with the samples to optimize render times, when i noticed only half my image was being rendered, even though i split the tiles perfectly so each gpu did half.

when i looked into my blender settings only one gtx 970 showed up, so i updated my drivers, after which none showed up; i restarted my pc, with the same result.

device manager and nvidia both detect 2 cards, but blender isnt detecting anything.


i noticed this too when i used upbge when browsing the settings. i thought it was just upbge.

i only ever use 2.74 on my gtx 970 system. but my laptop gt 755m works fine with 2.78c which i sometimes use with Manuel Lab addon.