Last time I talked to the programmer of Core Temp, he was too busy to get his program updated for Sandy Bridge so I can't recommend using it until it is updated.

What CPU-Z reports when a CPU is lightly loaded has been designed for consistent CPU-Z validation purposes so it might not be the best source of information if you need to know exactly what your CPU is doing internally. HWiNFO32 used to be similar to CPU-Z but with Sandy Bridge, CPU-Z has made some changes so I'm not sure how they compare now.

RealTemp, i7 Turbo, ThrottleStop and the RTCore.dll RealTemp RivaTuner plugin follow the multiplier reporting method outlined in the Intel November 2008 Turbo White Paper. When a CPU is lightly loaded and some of the cores and threads are using the various C States, the average multiplier tends to jump around quite a bit. When turbo boost is rapidly cycling on and off, the average multiplier can also increase and decrease rapidly. That's the data my software reports. It's not always pretty but by using high performance timers within the CPU, it's extremely efficient and accurate at reporting the multiplier transitions.

I like seeing exactly what the CPU multiplier is doing internally while other users prefer to look at a stable multiplier like CPU-Z reports.

Bios C State settings like C1E/C3/C6 and the Control Panel - Power Options - Minimum processor state setting both interact with each other and determine the average multiplier your CPU operates at. Play around with those and that might help you understand what software is telling it like it is.

Here's another program I wrote that lets you play around with some of these settings without having to reboot when testing.

ThrottleStop 2.99.6
http://www.mediafire.com/?26tu6cjmgu8ze9a