i had this problem now with SU 15 beta, PC shut down in flight completely. It happened when the scenery had this annoying stutter which seems to induced by SU15 in some areas. PSU 1200w and only 2 years old.
Update:
i guess the new 24.5.1. AMD GFX driver is inducing the shut down as it produces artifacts and weird things when running the new final fantasy benchmark…
will roll back to 24.4.1