Lekuo SouthBridge Max PCIe 4.0 Multi-Function Expansion Card - No Motherboard Bifurcation Required

Product Specifications

Product Description

Driver Download

Document Download

Q&A

Brand

LEKUO

Product Name

Lekuo SouthBridge Max（No Motherboard Bifurcation Required）

Model

PB65MX3

Output Ports

4 x M.2 NVMe, 4 x SATA 6Gbps, 2 x 10Gbps USB-A, 1 x 10Gbps USB-C, 1 x 20Gbps USB-C

PCIe Standard

PCIe Gen4 x4, backward compatible with Gen3/Gen2/Gen1

Compatible Slots

PCIe x4, x8, x16 slots

Product Dimensions

174 x 69mm

System Support

Windows，Linux，Mac OS

Package Contents

1 x Lekuo SouthBridge Max, 1 x User Manual, 10 x Screws, 2 x 6.5mm Copper Stands, 2 x 1.5mm Copper Stands, 1 x Short Metal Plate

Lekuo SouthBridge Max: PCIe 4.0 Multi-Function Card (B650 AIC, No Bifurcation Required)

Product Overview

This adapter card is based on the B650 southbridge chip and transforms a native motherboard chipset into a standard PCIe expansion device. Via a PCIe 4.0 x4 upstream interface, it provides four M.2 NVMe slots (two on the front supporting x4, two on the back supporting x2), four SATA 6Gbps ports, two 10Gbps USB-A ports, one 10Gbps USB-C port, and one 20Gbps USB-C port. Its M.2 interfaces feature intelligent bandwidth allocation: when only the front dual-drive slots are in use, both operate on x4 links when all four slots are occupied, the system automatically adjusts to x2 links(The interface shares the PCIe 4.0 x4 upstream speed). This card is suitable for high-end PCs, workstations, media processing, NAS systems, and gamers, providing a one-stop expansion solution for high-density storage and high-speed peripherals.

Features

• PCI Express
- PCIe Gen4 x4（64Gbps Theoretical Uplink Bandwidth）, backward compatible with Gen3/Gen2/Gen1
- Supports a data transfer rate of 16 GT/s per lane
- Supports three power-saving modes: L0, L1, and L1SS
- PCI MSI, MSI-X, ASPM, AER, LTR, VC

• 4 SATA Ports
- Supports four SATA ports with a maximum data transfer rate of 6 Gb/s.
- Supports first- and second-generation SATA standard devices.
- Complies with the SATA 3.3 specification.
- Supports AHCI 1.3.1 mode.
- AHCI mode features the following functions: ➢ DIPM ➢ HIPM ➢ Hot-plug detection and notification ➢ NCQ mode ➢ Device sleep mode

• USB Ports
- Supports 2 USB-A (10G) ports, 1 USB-C (10G) port, and 1 USB-C (20G) port;
- Supports all xHCI 1.1 features;
- Compatible with traditional keyboard/mouse devices;
- Supports wake-up functionality in S3/S4 modes;
- Supports port disabling via independent control.

• M.2 Ports
- Compliant with PCI Express Base Specification Version 4.0
- Compliant with PCI Express M.2 Specification Version 1.1
- Supports PCI Express link power management
- Supports M.2 form factors: 2230/2242/2260/2280
- Supports M.2 M Key
- Supports four standard M.2 interfaces, with the two front M.2 interfaces (M.2_A, M.2_C) supporting X4 links, and the two rear interfaces (M.2_B, M.2_D) supporting X2 links.
Note: When all M.2 slots are occupied, all four M.2 slots operate at x2 bandwidth. If only the two front M.2 slots are used, they operate at x4 bandwidth; if only the two rear M.2 slots are used, they operate at x2 bandwidth.

• 6-Pin — addresses the power delivery ceiling only; the 64Gbps shared bandwidth is unchanged.

System Support

• Windows

• Linux

• Mac OS

Complete Package Contents

1 x Lekuo SouthBridge Max
1 x User Manual
10 x Screws
2 x 6.5mm Copper Stands
2 x 1.5mm Copper Stands
1 x Short Metal Plate

Related Downloads

1. Datasheet_ PB65MX3

Download

Q My motherboard BIOS has no PCIe bifurcation option. Can I still use all four M.2 slots on this card?

A Yes — that is exactly what the PB65MX3 is built for. It carries an onboard B650 chipset, so lane allocation for the four M.2 drives is handled on the card itself. The host only needs to provide a single standard PCIe x4 link: no x4x4x4x4 bifurcation, no BIOS tweaking. Whether you run a mid-range board, an older platform or a branded OEM system, all four drives are detected as long as you have one free PCIe slot.

Q How is it different from a regular quad-M.2 adapter card?

A A conventional quad-M.2 card is essentially a passive lane breakout: it routes four x4 lanes split by the motherboard to four sockets, so whether the bays work at all depends entirely on your board. The PB65MX3 is a motherboard chipset turned into an expansion card. With a single PCIe 4.0 x4 uplink it natively provides 4× M.2 NVMe, 4× SATA 6Gbps, 2× USB-A 10Gbps, 1× USB-C 10Gbps and 1× USB-C 20Gbps. One card replaces an M.2 card, a SATA card and a USB card — while occupying just one slot and one link.

Q How is bandwidth distributed across the four M.2 slots? Will speeds drop with all four populated?

A It uses intelligent lane allocation. With only the two front slots populated (M.2_A / M.2_C), both drives run at x4. With only the two rear slots (M.2_B / M.2_D), they run at x2. With all four populated, every slot drops to x2 and shares the PCIe 4.0 x4 uplink (~8 GB/s theoretical; real-world sequential throughput is typically in the 6–7 GB/s range depending on SSD model and platform). For maximum per-drive speed, use the two front slots. For capacity — storage pools, media scratch drives, NAS cache — populate all four: even at x2 (Gen4 x2 ≈ 4 GB/s theoretical), each drive is still far faster than a SATA SSD at ~550 MB/s.

Q Which M.2 SSDs are supported? Do short drives like 2230/2242 fit? Is there a capacity limit?

A It supports M.2 M-key NVMe SSDs compliant with PCI Express Base Spec 4.0 and PCIe M.2 Spec 1.1, and is backward compatible with PCIe 3.0 drives. Supported form factors are 2230 / 2242 / 2260 / 2280, covering virtually all consumer and many enterprise NVMe drives. Capacity is set by the OS and drive controller — 1TB / 2TB / 4TB / 8TB per drive all work. One caveat: M.2 SATA drives (B-key or B+M-key) are not supported in these slots.

Q What are the four SATA 6Gbps ports for?

A The four ports are SATA 3.3 compliant and work with SATA I / II devices at up to 6 Gb/s — ideal for 2.5" / 3.5" HDDs and SATA SSDs used as cold storage, backup drives or NAS array members.

Q How fast are the USB ports, and what can I connect to the 20Gbps USB-C port?

A You get 2× USB-A 10Gbps, 1× USB-C 10Gbps and 1× USB-C 20Gbps on an xHCI 1.1 host controller. They work with legacy keyboard/mouse devices, support wake from S3/S4 and allow per-port disabling — useful for industrial PCs and shared machines. The 10Gbps ports suit portable SSDs, flash drives, capture cards, printers and wireless dongles; the 20Gbps USB-C port suits 20Gbps NVMe enclosures (typically 1.5–2 GB/s real-world sequential), high-speed card readers, 4K capture gear and VR headsets. Because these ports hang off the card's own chipset, they do not consume your motherboard's native USB controller resources — effectively an extra high-speed USB root hub.

Q Do I need to install drivers? Does it work on Windows, Linux and macOS?

A It officially supports Windows, Linux and Mac OS. Built on a mature B650 chipset, NVMe and AHCI ride on the standard protocol stacks inside the OS, so Windows 10/11 and mainstream Linux distributions are typically driver-free (Linux ships in-kernel drivers). One thing to keep in mind: on macOS, USB port behaviour varies by machine and OS version, and third-party USB host controllers may show speed or power-delivery differences on some Apple systems — verify on your actual hardware.

Q My board is PCIe 3.0 only, or only has an x16 slot free. Will it work, and how much performance do I lose?

A Yes, both work. The card has an x4 edge connector and fits PCIe x4, x8 or x16 slots (including graphics-card-length slots), and it is backward compatible with Gen3 / Gen2 / Gen1. Bandwidth reference: PCIe 4.0 x4 uplink is ~8 GB/s theoretical, about 4 GB/s per drive with all four populated; PCIe 3.0 x4 is ~4 GB/s theoretical, about 2 GB/s per drive with all four populated. Even on a PCIe 3.0 board, ~2 GB/s per drive is plenty for scratch disks, storage pools and NAS use — you'd only want a Gen4 platform for sustained multi-drive workloads such as 8K multi-track editing. The card also supports L0/L1/L1SS power states and ASPM for lower idle power.

Q What are the card's dimensions? Will it fit an ITX case, a NAS chassis or a 2U server?

A The board measures 174 × 69 mm with a low-profile design, and a low-profile bracket is included in the box — so it fits half-height cases, 2U/3U servers and most NAS chassis. On ITX boards, which usually offer only a single PCIe slot, the "one card replaces three" density advantage really shows. Package contents: 1× expansion card, 1× user manual, 10× screws, 2× 6.5 mm standoffs, 2× 1.5 mm standoffs, 1× low-profile bracket.