Scrap that. The reboot was instant. How very odd... That was with the overclock applied.
What was different this time sorry, thread's getting hard to read!
so all scenarios are:
Overclocked normal - slow shutdown
Overclocked safe mode - fast shutdown
Stock normal - fast shutdown
Stock safe mode - fast shutdown
is this right? what's your current drive configuration, any RAID setup, how many HDDs, all SATA and using AHCI?
Very strange, was the overclock re-applied identically, i.e. from a profile? or did you manually reapply it?