Buddy, 1156 and 1155 use the same exact mounting pattern; no difference at all. And the MUX isn't any taller than your V6GT either. Your V6GT lists a height of 165mm. The MUX is listed at 160 mm tall, which is actually 5 mm shorter than the V6GT. The V6GT also looks to be pretty darned wide too and probably will have interference problems with the first ram slot if your ram has tall heatspreaders. Plus, if he decides to move to a different platform down the road, Thermalright has a proven track record of making new mounting kits for their heatsinks and most of their heatsinks use mounting equipment with commonality between them. As for cooling ability, I would bet that the MUX will hang with the V6GT, if not beat it. I haven't tested the V6GT, so I can't definitively say that, but that's my gut feeling. And that also comes from my experience with the heatsink it's based on, the True Spirit.