Well, you then should investigate a bit more… cause they do.
Version 19 Date 13-06-2013 is considered to be the best for 306A9 (IB) regarding OC values. Latest one released by Intel is 21.
The r2 had a beta UEFI bios transition. You want to “play” a bit with it, then cross flash on your r1, if you’re willing to take the risks.
EDIT: @RayeR [OFFER] Intel CPU Microcode Archives - Special Topics / CPU Microcodes - Win-Raid Forum (level1techs.com)