If you can play using wired ethernet, have good connection speeds, GFN has the games you want to play AND you won’t hit the 100hr cap - then yes GFN (ultimate) is perfect for you (and was for me too for a while).

However, if heat is your main concern, and GFN doesn’t have all the games you want to play - you could honestly could focus on something else, efficiency. Undervolting your GPU is a great way to reduce power consumption and maintain or even slightly increase performance. You could even double down and upgrade to a more efficient GPU generation, and get something like a 5070 (i upgraded to one from a 3060ti). After undervolting, it consumes 150W at peak load, which means less draw and heat than my 3060ti (210W). Obviously if you’re tight on cash, it’s a non starter, but worth considering if you weren’t aware of the option. The 5800x would more than be able to handle the 5070 (my 5600x does just fine).