Honestly, haven't tried beyond 2.23v vdimm so not sure but from what I done so far you can see it doesn't scale much i.e. 585mhz 5-5-5-15 at 2.1v then 595mhz 5-5-5-15 at 2.23v, only 10mhz more so I'd say doesn't scale that well (not comparing to micron D9GMH/D9GKX).

Also remember it depends on what you're testing - you definitely need more vdimm for folks testing speeds with dual or quad super pi 32m instances compared to someone testing single super pi 1m and 2m passes or folks using quad core vs dual core cpus