Here's a look from two directions:
CPU TDP 77W
GPU TDP 55W
Mobo + other stuff <50W
benchmarked the P8H77-I with an i7-3770K and found it drew 92W while running Cinebench. I'm assuming this is power draw from the wall (they don't list their PSU, other components or procedure...bleh). If they had an awesome 90% efficient supply, this leads to 83W draw from the PSU. The HD 7750 has a TDP of 55W. So, that's 138W under heavy CPU/GPU load.
My guess is it would be fine under normal loads and maybe be iffy if you run Prime95 + Furmark.