Capacity and voltages
Being able to deliver a capacity is one thing, doing it correctly is another thing entirely. The ATX-specification requires voltages to have a maximum deviation of 5% in order to guarantee stability. This means that the important 12V rail has a minimum of 11.40 and a maximum of 12.6 volt. The 5V-rail on the other hand has a minimum of 4.75 and a maximum of 5.25 volt.
The voltages that the Prime Gold and Platinum power supplies offer are more than solid, and are well within the desired margins.