Lower temperature will be achieved by lower ambient temperature AND/OR reducing clock speed and power consumption. If your rigs were in a freezer then you would be able to expect a drop in temperature. However, this is not a practical solution. I manage my cards by setting a temperature threshold. When a card hits that temp the fan is increased and the power reduced. Your best bet is to manage your rigs in a similar fashion. I'd set it so that the power and temp was set lower, you can still raise clock speeds (small increments until instability) and go from there.
Thank you for your reply...for some reason I do not see the voltage being activated in afterburner...I can set the temperature as threshold (not to go above 88C for instance). So fans being triggered does not draw more power consumption? I thought if they trigger less the less electricity they spend