We have a lot of amd based rigs in the midlands area of the uk.
the -ttli feature is very very useful
its been VERY hot today and yesterday
set -ttli 70 on the config file of each rig about three weeks ago

nothing overheated over these last few days.
everything throttled back in the heat of afternoon . very nice.
and they speed up again at night.

we use ghost spectre windows 10 - no updates no bloat and no telemetery.
mix of rx5700 , 580s, 5600s 470s 480s all sorts. amd driver 20.9.1 or later

a lot of folk dont read the readme file that comes with phoenix
you should - the feature you need is probably described in the readme.

so top tip - set -ttli 70 and maybe even -mi 8  in the summer heat
prevent damage to your cards and rigs