It is safe for the fan to be at 100% but at 100% the bearings in the fan may fail sooner. To me 100% isn't really necessary, and at 100% most video cards are just way to loud. I would say download something like evga precision X or msi after burner. and just use the default automatic fan curve that they have set for you. normally I run my video cards at a max speed of 60% to keep things relatively silent, but 70% is also acceptable to most people. But for the most part for an average user that isn't a silence freak, the default fan curve that comes with some of the utilities is sufficient enough for cooling. If you have an evga card or asus card just use their overclocking utility fan curves, Msi doesn't really have all out that great of a fan curve.