The power supply either has a heat related short that shut it down, or some thermal protection that shut it down (in a no-name PSu that's exceptional).<BR>Suggestions: check that the PSU fan is ...

Screenshot from Der8auer's video above, showing >150℃ temperatures on his PSU wiring. Instead, Der8auer relates that his own personal RTX 5090 FE card may be suffering a similar fate soon.