Server connector gallery
Here’s a list of some common connectors for PCs and servers. Many are named like SFF-1234. The corresponding standard doc may be found in the SNIA website.
SAS / U.2 / U.3
SFF-8482 Serial Attachment 2X Unshielded Connector
Our good old SAS connector. Supports two links, though in most cases only 1 link is used.
SFF-8639 Multifunction 6X Unshielded Connector
Commonly known as “U.2”. It has 6 lanes and can carry SAS or PCIe x4 signals, as long as the controller supports it. Note the first two SAS lanes are not shared with the 4 PCIe lanes. Ignoring MultiLink SAS (SAS2 & SAS3) for now, and again commonly only one SAS lane (SAS0) is used.
SFF-TA-1001 Universal x4 Link Definition for SFF-8639
Commonly known as “U.3”, SFF-TA-1001 redefines the signal in the SFF-8639 connector and make SAS and PCIe share the same lanes. So only 4 lanes are needed. U.3 drives are required to support U.2 hosts, but U.2 drives won’t work in U.3 hosts.
MiniSAS
SFF-8087 Mini Multilane 4X Unshielded Connector Shell and Plug
Internal MiniSAS, typically can be broken out into 4 SAS connectors.
SFF-8088 Mini Multilane 4X Shielded Connector Shell and Plug
External MiniSAS, suitable for usage outside a case.
MiniSAS HD
SFF-8643 Mini Multilane 4/8X 12 Gb/s Unshielded Connector (HD12un)
Internal MiniSAS HD is the successor to the MiniSAS connector. It also has 4 high speed signal lanes, and supports higher speed. Can be broken out into 4 SAS connectors or used for a PCIe x4 device. The actual protocol supported depends on the controller. It is a popular controller-side connector for U.2 SSDs, so it was, for a while, referred as the “U.2” connector. Now “U.2” usually referrs to SFF-8639.
SFF-8644 Mini Multilane 4/8X 12 Gb/s Shielded Cage/Connector (HD12sh)
External version of the MiniSAS HD connector.
Note there are multiple other specs defining basically the same thing:
- SFF-8613 Mini Multilane 4/8X Unshielded Connector (HDun)
Defines the footprint and dimension of the unshielded connector. - SFF-8614 Mini Multilane 4/8X Shielded Cage/Connector (HDsh)
Defines the footprint and dimension of the shielded connector. - SFF-8673 Mini Multilane 4/8X 24 Gb/s Unshielded Connector (HD24un)
Almost the same as 8643, but for SAS-4 24Gbps rather than SAS-3 12Gbps. - SFF-8674 Mini Multilane 4/8X 24 Gb/s Shielded Cage/Connector (HD24sh)
Almost the same as 8644, but for SAS-4 24Gbps rather than SAS-3 12Gbps.
SlimSAS
SFF-8654 0.6mm 4/8X Unshielded I/O Connector
SFF-9402 Multi-Protocol Internal Cables for SAS and/or PCIe contains the pinout for this and multiple other connectors.
SlimSAS comes in two different width called “SlimSAS 8i” or “SlimSAS 4i”, which have 8 or 4 high speed lanes respectively. The protocol running in the wire depends on the device, typically PCIe or SAS. For example, a SlimSAS 8i connector can connect to two PCIe x4 U.2 drives using a split cable.
Some SlimSAS connectors have extra plastic “ears” on the corners. These parts hold the metal piece of the socket and make the connection more sturdy.
Some manufactures make non-standard “Low Profile” SlimSAS connectors. They are not thinner but are shorter than the standard connector when the two parts are mated. The gold finger PCB retracts into the plug to about the same position as the metal latch. Not to be confused with the above one that has the “ears”, the PCB there still extends beyond the latch. The low-profile plug/socket is not compatible with the standard ones. Here’s a picture and the datasheet from Amphenol SlimSAS LP Cable Assemblies Technical Datasheet.
MCIO
SFF-TA-1016 Internal Unshielded High Speed Connector System
MCIO is probably the successor of SlimSAS and is for highspeed PCIe/SAS signals and comes with multiple widths. The width is identified by their pin count rather than lane count:
- 38 pin: 4 lanes. Note this pin count matches SlimSAS 4i.
- 74 pin: 8 lanes. Note this pin count matches SlimSAS 8i.
- 124 pin: 16 lanes.
- 148 pin: 16 lanes with more sideband signals.
SFF-TA-1033 Internal High-Speed Cable / Modular Connector System
A special type of socket derived from SFF-TA-1016, by bundling one or two 74 pin sockets and a power socket together.
CDFP
INF-TA-1003 400 Gb/s (16 x 25 Gb/s) Pluggable Transceiver (a.k.a. CDFP MSA)
SFF-TA-1032 Multi-lane External High Speed Cable System
CDFP is a relatively new external connector type designed for PCIe 5.0 and higher speeds. Recall that the external MiniSAS HD is only defined up to PCIe Gen4. The SFF-TA-1032 doc defines x4 and x8 width beyond the MSA (only x16).
The SFF-TA-1002 family
SFF-TA-1002 Protocol Agnostic Multi-Lane High Speed Connector
REF-TA-1012 Pin Assignment Reference for SFF-TA-1002 Connectors
Sometimes known as “Gen-Z”, SFF-TA-1002 is generally a connector designed for PCB edge connection. It’s popular in datacenter and there are multiple different device form factors that utilize this connector. This connector also have multiple width:
- 1C: generally carries 4 lanes
- 2C: generally carries 8 lanes
- 4C: generally carries 16 lanes
- 4C+: 16 lanes plus extra sideband signals.
SFF-TA-1020 Cables and Connector Variants Based on SFF-TA-1002
SFF-TA-1020 defines a new 4C-HP width for delivering power. It’s similar to the 4C+ connector, but the plastic key width is different, preventing insertion of a wrong board. It also defines a cable plug, similar to MCIO.
OCP NIC 3.0 Design Specification
OCP 3.0 is a standard specified by the Open Compute Project. It primarily defines a form factor for server NICs, and uses SFF-TA-1002 as the connector. ServeTheHome has a great article talking about OCP 3.0: OCP NIC 3.0 Form Factors The Quick Guide
SFF-TA-1006 Enterprise and Datacenter 1U Short Device Form Factor (E1.S)
SFF-TA-1007 Enterprise and Datacenter 1U Long Device Form Factor (E1.L)
SFF-TA-1008 Enterprise and Datacenter Standard Form Factor (E3)
SFF-TA-1009 Enterprise and Datacenter Standard Form Factor Pin and Signal Specification (EDSFF)
EDSFF (Enterprise and Datacenter Standard Form Factor) is a form factor designed for SSD storage devices. There’s an introduction on the SNIA website: SSD form factors. These devices also use the SFF-TA-1002 connector, typically 1C for 4 lanes.
OCuLink
SFF-8611 MiniLink 4/8X I/O Cable Assemblies for the cable plug
SFF-8612 MiniLink 4/8X Shielded Connector for the receptacle
OCuLink is yet another connector capable of carrying SAS / PCIe signals up to PCIe 3.0. Despite being an internal connector, it’s popular in the MiniPC market, as a replacement for Thunderbolt to connect external GPUs. It also has two width options: OCuLink 4i for 4 lanes and OCuLink 8i for 8 lanes.
