The 560 is overkill for wow, left alone defense grid or minecraft. I know because my GTX260 was able to play wow at Ultra (laggy in raids though). And so that's a good choice.
PSU is enough for the 560.
That board is horrible, get a least a Z77. Get this at leasthttp://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627&IsNodeId=1&Description=z77&name=Intel%20Motherboards&Order=PRICE&Pagesize=20
Your board doesn't have pcie 3. Don't let people tell you pcie 3 and 2 are same, that's bull.