I've had many GPUs survive 4+ years of high-load usage running in the 70-75C range.
Targeting 50C is WAY excessive, and the only cases of 50C GPU temps with 50% or less fan I've ever had were on gear in an A/C room on risers, or the "outside" card in a "no case" rig with all cards on the MB, or a rig with ONE card in it - and the card was set to run at "efficient" settings.

Water cooled/hybrid is another story, water cooling the GPU is a lot better at keeping the temp down - at a significant cost for the higher-end cooling solution.