And one open to the floor but directed at Ben and cscape: is it ok to run these long term at 70-75C?
The higher the temperature, the quicker the chips will wear out, but I don't have hard figures about the expected lifetime at different temperatures. (I don't know that anybody has ever done a thorough characterization) However, considering that the reward of mining goes down as the difficulty rises, I would expect the optimal to be closer to 70-75 than to 50-55. But that's just a WAG.