I'd change the powersupply to something else as cooler master psus aren't the best as you can find better quality ones for a similar price such as the
NCIX.com - Buy Antec Earthwatts Green 500W Power Supply ATX12V V2.0 Active PFC 80PLUS Bronze 80MM Fan - Antec - EA500D-Green - in Canada NCIX.com - Buy Corsair Builder Series CMPSU-500CXV2 500W ATX Power Supply Active PFC 120MM Fan *3 Year Wrty* - Corsair - CMPSU-500CXV2 - in Canada
For your gpu it'd help if you name specific games you play since a gtx 550 can handle CS no problem but for BF3 it might run into some hiccups because FPS is a bit vague.
CPU wise the i7-3930k is a beast but if the most demanding thing is running excel, I just think that's a waste and unesceary as you can get away with something much cheaper if you're just running excel.
For cooling, you'll be fine with air cooling because you stated you have no intentions to overclock, the stock heatsink will probably do the job for ya.