Right now we have no information on how to identify the (seven!) separate KFSN4-DRE versions that were produced:
A way of identifying the versions is necessary for those looking for the two boards (KFSN4-DRE/iKVM/IST, KFSN4-DRE/SAS/iKVM/IST) which support hex-core AMD Opteron 2400 series (Istanbul) CPUs.
The easiest one to identify reliably is the KFSN4-DRE/2S which has a second PCI-E slot (all others have only one).
Additionally, boards with SAS capability can be identified by the presence of an LSI SAS1064E chip next to the unpopulated PCI-E slot. Alternatively, looking for the 4 SAS ports at the edge of the board does the same. As an example, see https://www.coreboot.org/images/7/76/Kfsn4-dre-mainboard-raptor-devsys.png
Those are just different BOMs, not different boards right?
Yeah, maybe so. I thought @eskere had said they tested with hex-core CPUs on a standard KFSN4-DRE but turns out they just tested with an unsupported CPU (Opteron 8300 series) and I didn't catch that. sigh