Hi,
I simply don’t know enough about graphic drivers etc… to continue the discussion in a meaningful way, but just suggesting a relatively easy option to at least rule out a possibility.
If @Niccolo_Terzi has already tried only connecting the monitor to the Geforce with no other connections (Intel to projector) it might be worthwhile to test.
It could be a total concidence of course, but what you are saying about OpenGL might be supported, as I’ve already posted above, this issue only appeared once Roon fixed another issue in the previous build for GeForce cards:
Edit:
Oh, just seen you have posted in the linked topic after I last looked/linked to it above. 