XPS 15 9570 - ASF2 Force off - What now ?

Configuration: XPS 15 9570 + TB16 - Windows 10.

I was playing a steam game recently (more than 120h in the playing) when I have got a first of a series of dark screens reboots. No BSOD, no warning, just a dark screen followed by one or more tries of reboot.

Long long story made short, I tried many things (not necessarily in that order).

- ASF2 force off: looking upon these dark screens, I accessed the BIOS logs; ASF2 Force off was pinpointed each time, in the category Power Events. No overheating event was ever reported

- monitored the temperature with HWMonitor and AIDA (quite high when playing, not very high during some crashes)

- Tried many things (gaming app or not):

- two different power supplies, with or without the TB16 plugged in.

- Tried on battery only

-  Sometime the crash will happen while watching a video on youtube or installing a software, or doing nothing (while I was not here, the XPS rebooted. I can't always blame Windows update, though.

- At some point, downloading a huge file from Steam will result in a very high bandwidth usage (45+Mb/s) and/or CPU usage (Avast would scan in real time the downloaded content). Re-installing steam would help somehow (the crash would happen after more time, say 10' rather than 1').

- For those who are interested in which game and various attempts (more or less summarized here), see https://steamcommunity.com/app/397540/discussions/0/2969523484453283487/

So at some point, I did the full set of recommendations: re-apply the latest driver updates (all of them), reset Windows10, clean-up the fans (quite dirty they were), clean-up and replace the thermal paste (NO THANKS to Dell, see my other post (reference below)), check as much as possible contacts of thing to the motherboard. Stop playing that game. Probably more that I can remember.

Now I get a crash "only" once every two-three days. I bought a 4-year total on site guarantee that expired 8 months ago.

Any advice ?

Gilbert