What are you going to be using it for, if it's just games 12GB isn't necessary. I'm certain it'll be able to handle those games easily, but could you more specific about the i7 and the case?
I'd halve the HDD drive and get an SSD if I were you, your sytem will be much snappier.
The particular model of the i7 and the brand/model/speed of the RAM you're going with would be helpful information. Keep that in mind next time you're ask for computer help so forumers can give you better help/advice. :)
Putting that aside, that rig should run basically any game you can throw at it at high/ultra. Have fun!