Software voltage monitors are notoriously inaccurate. If you are concerned about your voltages, then get yourself a cheap digital multimeter and read the voltages directly.
Your +5v, +12v and +3.3vdc readings should all fall within 5% of the nominal. The vcore will differ depending on your processor, and the -5v and -12vdc have a 10% tolerance, though many motherboards no longer use those voltage outputs. Keep in mind that newer systems and power supplies will have more than one 12v or 5v power source (also known as a rail), so you might want to check each connector.