When playing Overwatch on Max I usually get 70 fps but my GPU gets to 160 fahrenheit, (Used to be 173 but I upped my fans). With other games on max I usually get 140 fahrenheit. (RX580 Sapphire 8gb vram)
Maybe other game you played is CPU heavy, and your CPU become a bottleneck so your GPU is not 100% used? Anyway, I dont think play on max setting is a good idea in ow, unless you dont care about being competitive. Set texture on high and SMAA to low and everything else set to lowest option will give you a lot more frames and lower input lag.
No VSYNC only Enhanced Sync