i just got 2 gtx460 i have 3 slots for graphics cards manual says pciex16_1 and pciex16_2 and pciex8 i had my sli setup in the pciex16_ and _2 but the gap between them was bad they was almost touching so i changed it to the other slot which is the pciex8 slot is there a difference manual recommends both pciex16 slots is there a difference in performance