Sure... if your bothered about the noise... run them lower... it has never been in-advisabl;e to run them at under 100% though.... Your average fan will LONG outlive the rest of your system.
P.S This is my fan profile:
Incedentally my GPU temp is rarely if ever above 60C
I Might have to replace my fan(s) a year or so sooner than you... but my CPU and GPU will last A LOT longer... Not to mention this argument is mute... since all the hardware will be replaced due to being out-of-date long before any of this happens.