I'm in the process of putting together a new machine mostly for gaming, and I'm not sure how much I should actually allocate to the Power Supply. I'm thinking a 750W cause I'm gonna have an i5-3570K and an HD 6870 with 8GB ram, and then 1-2 7200rpm drives and a standard optical drive. I'm trying to save money as much as possible, but was wondering, how cheap is too cheap?