Comment # 1 on bug 1046957 from Takashi Iwai

Is it with Nvidia binary-only driver or nouveau?  You can check without the
nvidia graphics driver but efifb whether it gives the difference.

Other than that, it's a bit tough to check without the detailed information
about your hardware.  Basically the way to track is to either check the
behavior change by disabling the h/w component one-by-one, or to try git
bisection.