The FM550 is an I/O module equipped with two external mini-SAS x4 connectors. I/O FMCs of this sort are typically used to provide inter-module connectivity via the front-panels of carrier cards fitted with similar interfaces, or fan-out to multiple external devices such as mini-SAS drives.

Eight full-duplex high-speed serial lanes connect through the DP[0:7]_M2C/C2M lines of the HPC FMC connector to the FPGA of the carrier card. The mini-SAS connector is designed for signalling up to 8.5Gbps, contingent upon support of this rate by the interfacing FPGA device.