You you got that right, if you increase the vdimm you have to watch that your qpi vlotage is not lower then 0.5V then your vdimm voltage.
There are people that run Qpi voltage 1,4V+ so i dont think its gona be a big problem. But you dont really need uncore clock that high, cause the gained performance is only benchable but thats all. You wont notice any difference while working. :p: