My duo is oveclocked from 2.13 to 2.68Ghz. Temp of cooling water was 33degr. Core temp is 1.2V. As I said before flat surface of the CPU touching heatsink is not perfectly flat( doesn't make flat impression on cooler and piece of glass eider) and this can cause poor heat transfer. I don't want to mess with it any more, but I'm tempted to test CPU with stock heatsink. Did you remove CPU from socket to lap it ??