MCIO vs SlimSAS

MCIO, short for Mini Cool Edge IO, and SlimSAS are two internal cable connectors that carry four or eight lanes of PCIe or SAS from a board to a backplane. MCIO is SNIA's SFF-TA-1016, Internal Unshielded High Speed Connector System. SlimSAS is SFF-8654, the 0.6 mm 4/8X unshielded I/O connector. Both use a 0.60 mm contact pitch and 38 and 74 contact sizes for x4 and x8. SFF-TA-1016 itself cites SFF-8654 as a similar connector.

SFF-TA-1016 Rev 1.3, dated November 15, 2024, also defines 124 and 148 contact sizes for x16 and lists signal integrity limits up to 112 GT/s PAM4. HighPoint's MCIO-PCIEX16-G5 has two x8 MCIO connectors and follows SFF-TA-1016 for sideband signals. Supermicro's X14DBI has MCIO PCIe 5.0 x8 connectors, each splitting into two PCIe 5.0 x4 links. Broadcom's 9600 series 24G SAS adapters use SlimSAS SFF-8654 internal ports, two x8 on the 9620-16i, on a PCIe Gen 4.0 host interface.

Match the standard number on both ends of the cable and ask for its rated speed. On the X14DBI, PCIe 5.0 NVMe runs over MCIO, and the Broadcom 9600 internal ports are SFF-8654. A cable sold for 24G SAS is not evidence of 32 GT/s PCIe 5.0 signaling.

Sources

Last verified October 30, 2026.