There were limited information regarding memory compatibility with KCMA-D8.
On the other hand, there were more information for KGPE-D16 regarding memory compatibility, and it seems the good RDIMM sticks for that board are mostly from either Micron or Kingston. There are few entries about Samsung and Hynix ones (like the ones I currently have, which don't work with coreboot).
Have anyone tested this board with latest coreboot and with either Micron or Kingston RDIMM sticks? I'm yet to rule out the possibility that Samsung or Hynix ones are generally not as compatible with coreboot as with Micron or Kingston ones.