We run all of our fans at a flat 80%. Seems to be a good compromise between good airflow, and not killing the fans.
Tried using 80% fan speed and about 6 out of 20 fan died after 3 months.... is it because of the sapphire brand I am using?
Sapphire fans are complete shit. All my cards are Sapphire and all of the fans have died in under a year using 100%. Now I use 80% so we shall see.