Good question. I've been OC'ing since the late 80's, and as would be expected, have had various issues which resulted in over heating CPUs. They auto-shutdown to prevent damage.
Mine have always booted right backup/performed well, after solving the problem.
Yes, the BT line seems a place where video gets hung a lot. Can you boot using the MB video output (pull the card), and disable Nvidia driver as you did, and then install web drivers, if your card requires them?