So I am trying to decide whether I should sell my 2 6950s and go with a single 7970 or 7950. The main purpose is for bitcoin mining with gaming being secondary since I just don't have the time like I used to. Currently my 2x6950s pull in about 650MH/s while undervolted at about 300w total system power (from Kill-a-Watt). Power consumption is not that much of a concern since I pay a fixed amount for utilities where I am at right now. The card would be watercooled. Any suggestions?