How did you measure voltage, if you use a multimeter it probably wont show the same numbers as the built in monitor.
And those values should be within spec.
5V is within 1,4% and 12V is witin 0.9%
IIRC correctly the spec is at least a 5% tolerance ans most computers will probably take up to 10% depending on line, load etc.
It also depends what you have running to drain each line. And look at the 3,3V line, is that 3,3 or 4,5....many things use 4,5V for the 3,3 volt line today.