PureOverclock posted a review on the Arctic Cooling Accelero GPU Coolers (X1/X2)

The X1 and X2 are drastically different from the NV silencer range that ruled the earth before it. They have introduced heat pipe technology into the equation - a first for GPU cooling. Arctic Cooling claims this improves the cooling efficiency over the NV silencer range.

Arctic Cooling Accelero GPU Coolers (X1/X2) Review