The lower voltages under load are called vdroop and this is normal and should not be confused with vdrop.
Vdroop is your friend as it keeps cpu voltage swings within normal limits.
Some claim that they need to enable some level of load line calibration (aka LLC) in the bios for stability with very high overclocks.
I've seen several instances in the forum with older motherboards where their highly overclocked systems passed rigorous stress testing with LLC enabled, only to randomly fail at idle. The amount of vdroop varies with different motherboard models. Some newer motherboards have several LLC options from mild to wild.
Check out AnandTech | Overclocking Intel's New 45nm QX9650: The Rules Have Changed, page 5
and AnandTech | Overclocking Intel's New 45nm QX9650: The Rules Have Changed, page 6 from 2007 for a detailed explanation.
For more information, search using:
You will find a wide range of opinions.
- vdroop vs vdrop
- load line calibration
- amd load line calibration
If your system is stable without LLC enabled, don't worry, be happy.