Have the same exact problems my screen has really bad tearing in games like PUBG, Fortnite, and Assassin's Creed. And my card runs around 77 degrees. Let me know if you had to return it.
Super bad screen tearing in games like PUBG and Assassin's Screen Odyssey. I Have an FX RX580 8GB gpu, Acer XG270HU monitor, 16GB ddr4 ram, intel i5-8600k cpu, Z370 mobo