熱 = less efficient, maybe due to the deteriorate of the parts.
Powerful enough to drive or not, usually you may just count the +12V trails, multiply it by the max current allowed, in this case:
12V x 36A = 432W, to be save you may assume it to be 432*80% = 345.6W
Then make sure all your parts in your computers, mainly CPU+GPU, do not consume more than 364.8W and things are fine.
For the heat, are you feeling it even your computer is at idle?