Im a fairly good pc builder and ive seen some weird issues but this one just has me stumped, ive had this issue once before but i cant remember how i fixed it for the life of me, the issue is that the computer works 100% perfectly a-ok until i install the gpu in which case i get no display and no power to any of the usb ports, no post codes, all fans and lights are on, i had been using the motherboard in a different system up until recently when i swapped it out for a new one due to the fan headers dying, at least i thought they did because when i turned on the system now they all work, i must have been missing something but thats besides the point, i just cannot think of why the whole system wont work when the gpu is installed