I'm building a new PC and when I put it together outside of the case, on top of the mobo box, everything booted, I got a post beep and was able to enter the BIOS. However, when I put everything into the case and try to turn it on absolutely nothing happens. I'm confused as to what could be grounding it. I've pulled it in and out of the case a few times and it works every time I pull it out. Help!