Yeah I misread one part my friend. I saw you say you had the same problem with default and did not see the part where you had put your OC back in.
I do recall asking you to list all changes to the bios that you made. As far as I can see you did not respond to that request. Hence I think quiet naturally assumed you had made none.
But all good.
Save your profile in BIOS tools.
F5 in bios please. Reset to optimised defaults.
Set multi to sync all cores
Set 48
Do not change anything else.
F10 and boot into OS.
Once in OS power down completely. Then after a few minutes power up and tell me if your CPU is still sticking 48x and does not follow the intel Speed Step or C states protocols.
I apologise for not getting that you had reset the same OC. But lets see if we can get this mystery sorted now that I am on the same page. I would still like to see ALL changes made to bios please.
To help us help you - please provide as much information about your system and the problem as possible.