DiLinKer LSI 94xx Tri-Mode Cable, 2x U.2 NVMe (SFF-8639) from One SFF-8643 Port, 75cm, with Power

A two-headed U.2 cable for LSI 94xx Tri-Mode controllers. One 36-pin SFF-8643 port on the card fans out to two 68-pin SFF-8639 drive connectors, 75 cm each, with power tails. Both heads carry NVMe over PCIe, which is only possible because the 94xx family can put PCIe lanes on its 8643 ports — on any other LSI card the same port speaks SAS and this cable does nothing.

Why this cable is controller-specific

• Only Tri-Mode controllers put PCIe on an 8643 port. Across the LSI range the SFF-8643 shell is used for SAS lanes. The 94xx generation is the one that can drive NVMe over those same pins, which is why this assembly is sold as an LSI94xx part and not as a generic U.2 cable. On a SAS-only HBA the drives simply will not appear.
• Two drives from one port, with the lanes split in the card. The split happens inside the controller, not in the cable, which is why nothing here needs power, firmware or a switch chip. Each head still presents a full x4 link to its drive.
• Power tails on both heads. Each 2.5″ U.2 SSD needs 3.3 V, 5 V and 12 V, and each head carries its own 4-pin power lead for exactly that. Drives in a powered backplane can leave them unplugged; bare drives cannot.
• 75 cm per head, correct on this listing. The old description on this page said 50 cm in one line and 75 cm in another. The part we ship is 75 cm end to end on each head — treat the 50 cm line as a typo, and measure your routing against 75.

Specifications

Compatibility

Works with

• LSI / Broadcom 94xx Tri-Mode controllers with SFF-8643 ports (check your card’s port configuration before ordering)
• 2.5″ U.2 NVMe SSDs (SFF-8639), any vendor
• Chassis with room for two drives within 75 cm of the card

Does not work with

• Any SAS-only HBA or RAID card, including earlier LSI generations — their 8643 ports carry SAS lanes and the drives will not enumerate
• SAS or SATA drives — both heads are PCIe-wired
• Motherboard 8643 ports — those are single-link; use our plain SFF-8643 to U.2 cable instead
• Splitting one head to two drives: each head is one drive, full stop

Typical deployments

• Two-drive NVMe mirror on a 94xx card. One cable, two SSDs, no backplane and no expander — the cheapest way to get redundant NVMe into a workstation-class build.
• Test bench with a Tri-Mode card and loose drives. Both drives sit on the bench next to the card instead of in a cage, so you can swap them without pulling the chassis apart.
• Small server where a U.2 backplane will not fit. Two cabled drives in a 2U chassis take less depth than a backplane plus its cabling.

Frequently asked questions

Is this the same as a normal SFF-8643 to U.2 cable?

No. A normal one carries a single drive from a single-link port. This one carries two drives from one port, and only works because the 94xx controller splits the lanes internally. Buy this for a 94xx card; buy the plain cable for a motherboard or riser port.

Which controllers is it actually for?

The LSI / Broadcom 94xx Tri-Mode family, where the SFF-8643 ports can be configured for NVMe. Because port configuration is a card-level setting, send us your exact model if you are not certain — we would rather confirm than have you return a cable.

The listing says 50 cm in one place and 75 cm in another.

The part is 75 cm per head. The 50 cm line came from an earlier description and has been removed; if you need a measured length before ordering, ask and we will put a tape on one.

Do both power tails have to be connected?

Connect the tail for every drive you actually fit. Each 4-pin tail feeds one 2.5″ U.2 SSD with 3.3 V, 5 V and 12 V; a drive with no power tail will not spin up, and there is nothing on the cable that substitutes for it.

Can I use it on a plain SAS HBA to get two drives?

No, and this is the mistake that costs people a return. A SAS HBA puts SAS lanes on its 8643 ports, so NVMe drives never enumerate regardless of cabling. For SAS or SATA drives on an HBA you want a 4x SATA breakout cable, not this.

How fast does each drive run?

Whatever the card gives it: each head presents four PCIe lanes to its drive. We do not quote a single GB/s figure on this page because the number depends entirely on the controller generation and the drive, and a made-up headline number helps nobody.

In the box

• 1 × LSI 94xx twin U.2 NVMe cable, SFF-8643 to 2× SFF-8639, 75 cm per head, with 4-pin power tails (SKU B07JM1H18S)

Every cable is continuity- and pinout-tested before it ships and carries a 24-month warranty. If a link does not train, send us the controller model and the backplane part number before returning anything — in most cases the cable is the wrong variant for the port, not faulty, and we would rather tell you that up front.

Related

• Single-drive SFF-8643 to U.2 cable, 75 cm
• PCIe 4.0 x4 to U.2 cable, no extra power needed
• All U.2 / NVMe cables and adapters