That's the best question yet.
People continue to promote offset voltage but I am having a hard time understanding why. If you want to save power when lightly loaded, why not just enable the low power C States?
Here is what I get with C1E enabled and C3 and C6 disabled while using the Windows Balanced power profile.
Power consumption at the wall is about 59 Watts.
When running a fixed voltage with both the CPU core and CPU package C States turned on, this drops to only 49 Watts of power consumption at the wall while using the Windows High Performance profile.
When combining offset voltages with the low power C States, power consumption drops down another 2 Watts to 47 Watts.
If you compare the core temperatures in the last 2 pictures you will see that they are identical which is a good indication that the CPU cores in both examples are getting the exact same voltage. The 2 Watt difference is probably due to the voltage regulator consuming less power when using offset voltages.
The over 0.5 volt difference that CPU-Z shows is meaningless because when a CPU core goes into C6, the core voltage drops down to virtually zero.
Instead of promoting offset voltages, why not start by enabling the low power C States. You end up with less power going to your CPU compared to running offset voltages with the C States turned off and it takes virtually zero testing to reliably combine C States with a healthy overclock. Offset voltages seems like a lot of work and is far more likely to limit a stable overclock compared to C States.
RealTemp T|I Edition
Edited by unclewebb - 5/21/13 at 2:03pm