Likely CAD stations are running nVidia hardware, which won't make you much. Make sure to do the calculations to determine whether you will actually make more in BTC than you would selling the extra power to the grid.
I do have some mining experience and am aware of the deficiency in mining in nVidia. All the cards are ATIs.
Don't forget to include mining-caused hardware MTBF reduction into your profitability calculations.
Good point, have now done so!