My primary uses will be playing video games (diablo III, starcraft II, assassin's creed III - because I get it free with the video card, and whatever else I feel like), watching blu-ray's, some video editing, and eventually some engineering modeling. I'm restricted to this budget, so I can't go with the i7 just yet. I'm worried about the motherboard and case. I could go with a 650W Corsair but I'm not sure I'll need it. Any Suggestions or glaring mistakes that I made?
Your ram is fine, you HDD (Hard Drive) Is not so much, it is more expensive for a not so great performance boost and a definite drop in storage, go w/ a 500gb wd blue or green, those are better (and cheaper) anyways. You do not need a blu-ray burner just blu ray reading drive, saves you 20$ right there. If you DO NOT PLAN ON OVERCLOCKING do not get the i5 3570k get the i5 3570 saves you some money andy you the same performance. The case is fine w/the mobo to answer your question. The only thing in this build i would really change is the 650, it isn't that great compared to the rest of the series, i would recommend the 7850, it plays all of those games listed @ max settings and performs better than the 650 @ higher resolutions. The PSU is perfectly fine for your build and even w/the 7850 it will be fine.