I have owned the Xeon E5-1620, 1620 V2, 1650, 1650V2, 1660, 1680V2( and will buy a Xeon e5-1660V3 next week.
All of these E5-1600 Xeons are unlocked with an open Coremultiplikator. Only about the E5-1620V2 it was or is said, and i had to believe know it today, that its coremultiplier is locked...