Got the laptop 2-3 days ago, opened it up, changed the crappy 1Rx16 modules and installed 2Rx8. After that, I started running some benchmarks to feel the awesomeness of the Ryzen 5800H (had a Strix with an i7 10750H).
First one to run was CPUZ benchmark. Mediocre score and huge temps!
In performance mode and in Turbo mode, I noticed I had temps around 91C to 95C
When running Cinebench R20, the temps were constantly 95 to 96C and the CPU was maxing out at 3.55GHz in Turbo mode and in Performance it even dropped to 3.5GHz all core boost.
I started some games, same, 91C to 94C. (Tomb Raider, Mafia Definitive, Metro Exodus)
That was it, I started searching the internet, to see wtf was going on. Some reviewers had good temps, some other didn't. That was curious. After that, I started searching reddit and I stumbled upon a guy that had a problem with a Zephyrus. He had pictures and he said that the Liquid Metal was not spread correctly over the CPU and after re-applying it the temps dropped.
Today, I decided to do the same with my laptop. I opened it and when removing the heatsink I made sure to remove it vertically so that I would not mess up the Liquid Metal and see how well it was applied.
And it was bad...
https://imgur.com/a/sutMm3M
After making sure it was nice and even with a cotton bud both on the CPU and the heatsink, I applied some liquid thermal pad K5-PRO (check the top left circle) and changed the thermal grease on the GPU (used some MX4).
Oh my, that made huge difference on temperatures.
Ambient temp: 26C - 27C
Cinebench R20:
Before the fix
Turbo mode: 95-96C, score ~4450. CPU frequency 3.55GHz
After the fix
Turbo mode: 84-85C, score ~4890. CPU frequency 3.85GHz
Metro Exodus (max settings):
Before the fix
Turbo mode: CPU 91 to 94C, GPU 86C
After the fix
Turbo mode: CPU 74C, GPU 74C
Now I feel like I have a Ryzen laptop and not my old 10750H laptop. Fans of course are also quieter.
So, if you got the skills, do it. Fix your ROG laptop high temps. It's 99% a thermal compound application problem.