As soon as I saw the discreet card I was wondering why you were going with a FM2 build??? For the same price you should be able to get a 6 core AMD AM3 that will a) OC better b) have 2 more cores. You are pretty much buying two video cards to only disable one.
AMD FX-6300 Six Core Processor Socket AM3+ 3.5GHZ 14MB 95W Retail Box