The 0v, the 3.3v, the 5v, the 12v, the -5v, or the -12v? What problem is it causing you?
I'm afraid you haven't given enough information. Each line on a power supply has an acceptable variance anyway, and depending on which line it is, +/- 0.7v could be acceptable.
In the absence of information, my only advice can be to try a different power supply.
"CPUs Don't Matter For 4K Gaming"... Wrong!
