Two things I have seen lately that can cause this...
1) Driver doesn't install correctly....removing Driver, cleaning registry with DDS(IIRC) utility, and reinstalling driver often fixes.....sometimes just removing and reinstalling is ok, but cleaning is good for Nvidia.
2) Windows 10 especially loves to muck with the video card power and usage settings and you have to go back into either Nvidia control panel or windows control panel and reset all settings to use max power and settings instead of a power saving mode.
Try these and get back to us if they don't fix it...if one does fix it, let us know too.
