When I have the default BIOS setting with SpeedStep enabled, I could tell that it's working because the CPU would drop down to 1600 Mhz idle and went back up if I'm working on something. I also saw the core voltage fluctuates in CPU-Z.
However, when I overclocked my CPU, the SpeedStep no longer works, it's at its max speed constantly, even when idle and it is enabled in BIOS. The only way I could get it to work is going to Windows Power Option and change the processor power management->minimum processor rate to 5%.
I find it strange that with default BIOS, the SpeedStep was working even though my Windows Power Option was set to Performance(with minimum processor rate @ 100%), and when I overclocked, I had to manually change Windows Power Option processor rate to 5% for it to work. Also, the core voltage no longer fluctuates in CPU-Z, even when it goes down to 1600 Mhz, is that normal?
Lastly, if it's normal for overclocked CPU to throttle with SpeedStep enabled, but the core voltage stays the same, does that mean I'm not getting the power saving it's supposed to do? Since it uses the same voltage, no matter if it's 1600 Mhz or 4500 Mhz.
Changing to performance power options usually disables speedstep. Although I'm not surprised sometimes it doesn't. There really is no point changing to performance unless you are having some issue. It just disables power saving features which should not be affecting performance anyways. You need to use offset vcore, not fixed. No you are not getting as much power savings.