Hello All, I know I'm late to the game, but I finally got around to upgrading the CPUs in my MP 4,1 to a set of 3.33Ghz Hex Cores. I decided against de-lidding the processors and using the washer method. Everything was going well until I stopped paying attention. Guess what I did? Yep, when clipping the tabs on the fan wiring harness I clipped the tabs AND a wire going to the fan. Did you know a new Heatsink is ~$140 and that they offer overnight shipping for an extra $50? I do. I got the replacement heatsink installed. It took a few times to get everything tightened enough to see all of the ram and for the fan wires to make contact, but it's running fine now. Is it hard to do? No. Is it easy to screw up? Yes. Would I do it again? Absolutely. Good luck everyone!