Yeah, this is a driver problem with NVIDIA. The last known driver to be compatible with K-BOOST is 376.33, which I am actually using for this exact reason. So, I recommend you find a way to switch to driver version 376.33 or earlier so that you can disable K-BOOST.
K-BOOST is also completely independent. It doesn't require EVGA Precision to be running in order to stay enabled. So, you could even enable K-BOOST and then uninstall EVGA Precision and K-BOOST will still be working. I don't know any more than this, such as why this is possible.
I also recommend that you don't attempt to delete things in Safe Mode in order to see if you can fix this because of the fact that you could uninstall EVGA Precision and K-BOOST will still be enabled (you should have tried to uninstall EVGA Precision, not delete any folders or files - that was just risky). I don't know how it works or what is making it continue to work even after Precision is completely removed from the system. Perhaps it's something being done at the driver level. So y'know what, perhaps the solution is to just uninstall your current NVIDIA display driver and then reinstall it. You shouldn't need to do anything other than a simple uninstall and reinstall of it. I mean, you shouldn't need to use DDU or anything like that. If that fails, then you should try driver version 376.33 or even an older one if you want. As long as it's not newer than 376.33.
Edited by TwoCables - 8/29/17 at 3:25am