turkey3_scratch :
Cooler Master (and other calculators) suck. Anyway, what PSu do you have? That system shouldn't use more than 200W when gaming.
I currently have the PSU that came with it from 3 years ago when I bought it, it looks like a Power Man 450W PSU.
Since my CPU and GPU use about 125W each is it still good for my 450W I have currently?