You can also go into your BIOS and see what your power supply outputs are.
Or download and run Speedfan, PC Wizard or Everest Free Edition…they will display PS outputs.
This box has a 350W Antec that is still hangin’ in there…I’m happy with those numbers which are within a 1% tolerence.
Up to 3% is supposed to be OK, but I wouldn’t want to live with that.
Many a mobo has been torched by a faulty power supply.