MB409A4_SlimSAS 8i (SFF-8654) to PCIe 4.0 x8 Adapter Card with Redriver

Bring PCIe Gen4 NVMe Connectivity to SlimSAS-Based Storage

The EXLink MB409A4 adapter card is designed to bridge PCIe Gen4 x8 slots with SlimSAS 8i (SFF-8654) connectivity, delivering up to 128Gbps of total bandwidth for high-speed NVMe signal transmission in advanced storage applications.

By integrating a PCIe redriver and optimized signal conditioning, the MB409A4 allows system designers and integrators to deploy SlimSAS-based NVMe solutions with greater flexibility, even in platforms requiring longer trace lengths or cable connections.
Designed for Flexible PCIe Gen4 Architecture

With a PCIe 4.0 x8 interface, the MB409A4 supports motherboards that enable PCIe lane bifurcation (x4 / x4). When bifurcation is enabled, the PCIe x8 interface can be split into two independent x4 NVMe links through SlimSAS 8i connectivity, supporting up to two NVMe SSDs via compatible cabling.

If the motherboard does not provide PCIe bifurcation support, only a single NVMe SSD may be recognized.
Expand High-Speed NVMe Storage with SlimSAS

The EXLink MB409A4 offers a scalable approach to expanding PCIe Gen4 NVMe storage using SlimSAS-based connectivity. *When paired with compatible SlimSAS 8i to dual SlimSAS 4i cabling and NVMe mobile rack solutions, system builders can configure dual front-accessible U.2 / U.3 PCIe Gen4 NVMe SSD bays from a single PCIe x8 slot.

This configuration simplifies high-density NVMe deployment without requiring specialized backplanes, making it ideal for servers and workstations requiring removable NVMe storage.

*Motherboard must support PCIe bifurcation (x4 / x4). This adapter card itself does not perform bifurcation.
Maintain Stable High-Speed Signals with Integrated Redriver

The MB409A4 integrates a PCIe Gen4 redriver to extend 16 GT/s, 8-lane differential pair signals, ensuring stable data transmission over extended trace lengths and cables.
This design supports full PCIe Gen4 performance even in complex system layouts where direct motherboard connections are not feasible.
PCIe Clock & Sideband Signal Management

To maintain accurate timing across connected devices, the MB409A5 features a built-in 100MHz PCIe clock buffer, supporting stable synchronization over extended routing paths.
In addition, buffered PERST#, WAKE#, and CLKREQ# signals enhance system stability and responsiveness, making the adapter suitable for enterprise-grade platforms and continuous-operation environments.
Flexible Platform Compatibility

The MB409A4 supports PCIe Gen2 through Gen5 host slots and can be installed in x8 or x16 physical PCIe slots on motherboards. With no operating system limitations, it is ideal for system integrators, OEMs, and solution providers building NVMe-enabled platforms across different hardware and software environments.
Simplify NVMe Upgrades with the ICY DOCK Selection Tool

NVMe Storage Selection Tool - an interactive guide that helps you find compatible mobile racks, cables, and adapters based on your system's NVMe slot type and installation needs.

Perfect for system integrators and DIY users alike, it eliminates the guesswork from building your ideal removable NVMe storage solution.

Main Features

•	PCIe Gen4 x8 interface with up to 128Gbps total bandwidth

•	SlimSAS 8i (SFF-8654) connector for high-speed NVMe signal transmission

•	Supports PCIe lane bifurcation (x4 / x4) for dual x4 NVMe configurations

•	Integrated PCIe Gen4 redriver for enhanced signal integrity over extended traces and cables

•	100MHz PCIe clock buffer for stable enterprise timing

•	Validated compatibility with ICY DOCK NVMe mobile racks and cables

•	Buffered PERST#, WAKE#, CLKREQ# signals

•	Universal PCIe slot support: PCIe 2.0 / 3.0 / 4.0 / 5.0

•	Requires motherboard PCIe bifurcation (x4, x4) to access two SSDs (This adapter card itself does not perform bifurcation)

•	CE/UKCA/RoHS/REACH compliant

•	2-year limited warranty

Specification

Model：	MB409A4
Compatible Drive Type：	NVMe
Support Slots：	Works with x8/x16 PCIe 2.0/3.0/4.0 or 5.0 slots on motherboards
Host Interface：	1 x PCIe x8 connector
Endpoint Interface：	1 x SlimSAS 8i (SFF-8654), pin-out defined by SFF-9402 Rev 1.1 (Tri-mode HBA/RAID card compatible)
Transfer Rate：	PCIe 4.0 x8 up to 128Gbps
Supported Operating Systems：	No limitation
Product Dimension (W x H x D)：	109.7 x 120.8 x 21.5mm
Product Net Weight：	45.5g
Package Gross Weight：	137.7g
Package Contents：	Device, mounting screws, user manual
Connector Insertion Rate：	5,000
Humidity：	5%~65% RH
Operating Temperature：	0°C to 70°C (32°F to 158°F)
Storage Temperature：	-35°C to 70°C (-31°F to 158°F)
Compliance：	CE, UKCA, RoHS, REACH
Warranty：	2 years limited warranty

FAQ

Q: How can I ensure my motherboard is compatible with the MB409A4 and can detect and read the two NVMe SSDs installed in it?

A: Your motherboard must meet the following criteria to recognize and read two NVMe SSDs:

The motherboard must support PCIe Bifurcation, which splits a single PCIe slot into multiple channels. For example, PCIe bifurcation can split an x8 slot into x4 / x4, or an x16 slot into x4 / x4 / x4 / x4 to support two NVMe SSDs. depending on motherboard design.
The combination of your motherboard and CPU must provide enough PCIe lanes to support all PCIe devices installed on the motherboard (including M.2 NVMe SSDs in M.2 slots).
The PCIe slot you use for installing the MB409A4 must have enough PCIe lanes and be correctly configured with PCIe Bifurcation.

Key Tip: The availability of PCIe lanes depends on your motherboard and CPU specifications, as well as how many PCIe SSDs and other devices you have installed. Therefore, we cannot guarantee compatibility with the MB409A4 based solely on a compatibility list. We strongly recommend consulting your motherboard supplier to confirm how many PCIe lanes are available in your system and whether any remaining empty PCIe slots can fully support the MB409A4 with two NVMe SSDs.

If you're unable to obtain this information from your motherboard supplier, you can follow the steps below to verify compatibility yourself (applies to Asus, ASRock, and AORUS motherboards only).

Step 1: Open the motherboard compatibility list and locate your motherboard model. As an example, we will use the ASUS AMD TUF GAMING B450-PLUS II motherboard.

Step 2: Once you find your motherboard model, check the PCIe slot that can support the MB409A4 based on the CPU you are using. For the ASUS AMD TUF GAMING B450-PLUS II, if you are using AMD Ryzen 1000/2000/3000/5000 series or 2000/3000 G-Series CPUs, the PCIEX16_1 slot on the motherboard can support the MB409A4. However, if you are using an AMD Ryzen 4000/5000 G-Series CPU, none of the PCIe slots will support the MB409A4.

Important Notes:

The method to check compatibility with Intel motherboards follows the same steps as the AMD example above.
PCIe slots share PCIe lanes, and the PCIe Bifurcation mode varies based on the PCIe slot's position. Not all empty PCIe slots have enough lanes for the MB409A4. If you have already installed devices such as GPUs, RAID, or HBA adapter cards, please check whether the remaining PCIe slots can support the MB409A4.
If the motherboard’s CMOS battery (coin cell battery) is low on power, the BIOS may revert to default settings after a power loss or system reboot. If the PCIe slot used by the MB409A4 was previously manually configured for bifurcation, this setting may be lost, reverting the slot to single-lane (x16 or x8) mode. As a result, the system may only detect one SSD. To ensure all SSDs in the MB409A4 are consistently recognized, we recommend periodically checking and replacing the CMOS battery to maintain the required bifurcation configuration over time.

To report a compatible or incompatible motherboard, or to check the compatibility of a motherboard not listed, please click here

Downloads

MB409A4 Product Image

MB409A4 User Manual

MB409A4 2D Drawing

EXLink MB409A4