On the rear side of the Thermaltake Toughpower 550W PSU, there is a lot of tiny square design of ventilation hole for the air exhaust to provide an optimal cooling solution.

Specification Label

There is specification label on the PSU that shows the each rails of the PSU. Look at the spec, the 2 x 12V rails giving optimized power distribution which is very powerful and total of the Amp at the 12V rail is at 38A.