Psu is a corsair RM850XPSU Model?
Motherboard?
It's a new setup brand newNew, or old setup?
Have you checked https://forums.tomshardware.com/thr...ng-about-post-boot-no-video-problems.1285536/ ?
Ive tried it with just it connected to the power supplyTry testing with case fans disconnected. There is a short somewhere.
Nope that doesn't work eitherThen try taking the board outside the case. Test with only CPU and CPU cooler installed, both 24 and CPU 4+4 pin power cable connected. See if the CPU fan does spin.