I have your CSE 512L- 200B 1 U rack mount case with a MBD-X9SCI-LN4-O. At the time we did not realize it did not come with a heat sink or HD bay, so we were testing without mounting the hard drive and used the heat sink and fan combo that came with the Intel processor. I received a heat sink model SNK-P0047P. Unfortunately I cannot see how this can be mounted on this motherboard. From what I can tell there is no way to screw this mount down with the included hardware and even if we could, it hits a capacitor beside the CPU.
The X9SCI-LN4 is equipped with Intel LGA1155/H2 socket. The correct 1U passive CPU heat sink is SNK-P0046P and 2U active CPU heat sink is SNK-P0046A4. The back plate BKT-0028L has been included in SNK-P0046P. For 2U active CPU heat sink SNK-P0046A4, it uses push-in pins and does not need a mounting back plate. The SNK-P0047P series 1U passive CPU heat sinks are for Intel LGA2011/R socket. A mounting back plate is not required for SNK-P0047P series CPU heat sink.