1) I agree here if you were a dedicated miner who just vents their air outside, but undervolting makes sense who pay electrical and cooling costs (ie. their cards are in a gaming machine). At that point your net revenue may come pretty down close to 0 after cooling costs unless you undervolt.
That is nonsense. Gross revenue is currently ~4x electrical cost. Even with 30% overhead for cooling it is >2x. Undervolting doesn't improve profits. Undervolting is useful in large farms where you simply can't handle the heat. I updated post above to show that.
Yeah, not quite sure why some of these ppl seem more concerned with efficiency than profitability. *scratch* But, then, I guess you also have people loading up with 7970's that will decrease in value like nobody's business, so..
Couple months ago, I never undervolted. Now I do so during the day only, because of heat issues (considering different solutions as to where I wouldn't have to do this). Then, I'm speaking from a perspective of anyone that gets electricity for, oh, I don't know, probably 15-20c or so or less. I pay ~8-9c per kwh.