Black screens though computer turns on..

Hello,
I'm getting black screens though my comp turns on..when I plug it into my external video card I'm getting a hardware change error and windows files missing or curupt.. I tried to reformt but all it does is loads..I read to press clear cmos so I did that didn't change anything except my fans go way faster now..I don't know if something is broken or what ? It runs on uefi interface as rock z68 extreme 3 Gen 3 motherboard and i5 2500k processor.. anyone know what may be wrong I'd appreciate any help..thanks!