If you still have issues you could try disabling realtime rendering in the viewport and to limit the frames per second.
To disable realtime rendering there is a little button with an arrow pointing down in the top left corner of the viewport. Toggle the Realtime option off. ( or just press Ctrl+R in the viewport)
To clamp the max frames per second you can type “t.maxfps 30” in the console command on the top right of the editor where it says “Enter Console Command”. ( you can experiment with different numbers other than 30 to get a balance)
Just by turning off Realtime rendering my GPU temps go from 71 deg to 42 deg and if I am just working on blueprints or something it works great.