So I was changing the case fans, after I put everything back together, I forgot to plug in the power for the GPU. I turned the pc on and I saw the white LED on GPU power port lid up and heard the fan spins like crazy (I don’t know if it was the CPU fan or the GPU fans), I panicked and immediately turned off the power supply.
Everything happened in less than 2 seconds, I’ve run some stress tests and gamed for a few hours and nothing bad happened (yet?) so I assumed everything is still fine (for now?).
What happens if I had left it on like that for longer? And why did the fan ram up like that?
For starters, not having the GPU power cable plugged in won’t damage anything. If you were to keep it powered on, you likely wouldn’t get any display output at all and more than likely would get an error or the OS would fail to boot.
The graphics card should also have a fail safe to keep from damaging itself on low power. It’s worth mentioning that the graphics card can pull some power from the PCI-E lane, but not enough to run the card on its own.
Seems to be OP’s concern. And for anyone coming along, otacon239 is 100% correct.