Originally Posted by badatgames18
hmmm.. not sure about that, sb imc is more resilient and is structurally different than x58/1366... rule doesn't apply as i have found out. You can function @ 1.65v with 2 dimms with a greater delta
There is no explicit statement regarding the absolute max differential voltage in the datasheets like their was for previous chips, but the DDR3 vddq limits are still between 1.425 and 1.575v, and the differential to vccio is ~0.5v (though admittedly the link between the two is much less clear in the second gen processors).
Many first gen core i7/5/3 systems ran fine at greater differentials as well, but in the absence of more specific information I tend to err on the side of caution.
He's probably fine with 1.65v memory, but I would still try to use as little vdimm as possible, even if the sticks themselves are specified to take higher.