ASUS PSU Guidelines for a higher quality PSU:
Under-rated POWER SUPPLIES
If the max amps on your supply are less than:
28A +3.3v, 32A +5v and 16A +12v then you need a better one IN MOST CASES. This is not always true and is dependent on how much hardware is in your rig. You may not have an issue now but overdrawing a power supply that is working today can lead to problems down the road and if/when that supply fails it can and will take out other components with it when it dies.