x16 R1, sudden BSOD's

Hi All,

i have an issue with my Alienware x16 R1. It worked very good the last couple of years, but since 3 days i get random BSOD's. I did the standard stuff already, updated all drivers / bios / windows updates. Did the Supportassist diagnostics, the Dell boot diagnostics. I even opened it up and cleaned the fans etc. 

The crashes can be every 5 minutes, sometimes it takes 3 hours. The temperature stays within limits, but, the part above the keyboard gets very warm. (even my screen is discolored because i have it always closed and use an external monitor).

Does anybody have ideas on how to further this investigation? Or is this a write off.