Hello.
We have kind of the same problem here.
Works at 120hz on an inferior computer than mine. (i5 vs i7 and 970 vs 980)
All my drivers are up to date. Not the case in other computer. Is it possible that there is an regression in gpu update ?
Here a SteamVr system report if it can helps.SteamVR-2021-02-25-PM_02_54_55.txt
Thanks a lot.