Voltages should be within 5% of rated as measured with a digital multimeter ($20 at Radio Shack). Onboard voltage monitoring is notoriously unreliable.
You should also measure the 12 volt rail at the mobo power connector and seperately at one of the HDD power connectors. Modern PSUs have dual 12 volt rails. One could be in spec and the other one out of spec (onboard monitoring only tells you what the mobo 12 volt rail is).