similar problem here
i have the same mobo and processor. i set my multiplier to 47 with 1.4v (yes i know, it's high but i was going to decrease voltage to see where it is stable), and speedstep function and all C states are enabled. I ran prime95 all night (9 hours) and it was stable, no errors and temps were in high 50s to mid 60s on all my cores.
i turned off the test and went on the internet for a while and no problems. when i came home from school and turned it on, browsed the internet, i got a BSOD.
right now i'm on the same settings and haven't blue screened yet, but when i check CPU-Z and Open Hardware Monitor while idling, my CPU cores are clocked at 4700mhz and voltage is 1.4 the entire time. It won't lower clocks when idle, nor the voltage. sometimes though, one of the cores goes to 1600mhz for a couple seconds and switches back to 4700mhz, and it alternates for a little bit but then they resume on full speed