I'm not sure where I read it, but sometimes you will see it advised to run GPU fans at 100%, or close to it, because the cooler temps make the GPU more power efficient. This is true, but lately I have also noticed that it's not often possible to find replacement fans for any given GPU. So if the card is meant to have a fairly long life cycle, it might be better to run the fans at a slower speed in hopes of extending their service life, which is what I currently do. Each card is different, but each one seems to have a point of diminishing returns where fan speed becomes excessive for the amount of extra cooling provided. I don't seem to find it necessary to run even the hottest cards at more than 75% fan speed in most instances, though. So how about my fellow DCers, do you just max out your fans, or try to find a happy medium?