it's safe to run the game at high fps, your concern is though that your GPU is running full blast all the time (at 100%) So the concerns then become: temperature, dust buildup (if air cooled) and fan motor wear. As you mentioned, your temperature isn't terribly high, so that's ok, but the sound could be indicative of increased strain on the fan motor. Open your computer up and check for dust.
Does the game have the option for V-sync?
if not try going through your nvidia control panel and see if you can set some 3d settings through there.