Allright, i just built my first rig this summer. I have An AMD x2 4200 (am2) on a gigabyte s5 590 SLI motherboard, with a BFG 7900gt OC Graphics card. The GPU is being cooled by a Zalman VF-900. Does the fact that the card came pre-overclocked mean that i cant OC it any further? How much farther could it go and would it be worth it in the long run?