1.309v is actually enough, I just usually bump the volts up by a tiny bit.
As for LN2, 6.6ghz max validation, doesn't scale over 1.75v even for validations, worse scaling when it comes to running actual benches. Considering how good it's on phase I was somewhat disappointed by the LN2 perf, and don't really want to try a 3rd time as 20L of LN2 is 100€+...