After enabling Hyper-V on my laptop running Windows 8, I noticed that Task Manager and Resource Monitor always showed the processor as running at full speed, as if Speedstepping was suddenly disabled. This is however not the case. What is really happening is that Hyper-V is virtualizing the CPU for the host OS (Windows 8) as well. Opening up CPU-Z reveals the real clock speed and multiplier of the CPU.

Hope this helps.