Lian Li B4 mATX Case Wood Black

Co-developed with DAN Cases, the Lian Li B4 mATX Case Wood Black is a remarkably versatile 21.3 litre chassis meticulously optimised to deliver uncompromising hardware compatibility within a compact footprint. This case features a refined real wood front panel that provides a striking colour and texture contrast to its sleek black steel frame. Despite its small size, users can confidently customise their configurations to support up to 358mm 4-slot GPUs, up to a 140mm ATX power supply, and cooling configurations with support for up to a 360mm liquid cooling radiator to the side and up to a total of nine 120mm fans (top, side, front, rear and bottom). To ensure massive modern graphics cards perform to their peak, it includes a dedicated anti-sag bracket, while its innovative modular design allows for both traditional horizontal and space saving vertical desk orientations. Complete with two pre-installed 120mm slim top fans for excellent thermal exhaust, tool-less removable panels, and a front USB 3.2 Type-C port delivering 20Gbps high-bandwidth connectivity, this highly adaptable case establishes a premium foundation for any serious small form factor enthusiasts.

Features

---

B4-mATX

Build Like Never B4

Co-developed with DAN Cases, the B4-mATX's modular design unlocks versatile build possibilities. With multiple colour, panel, and layout options, plus an optional accessory, it adapts to a wide range of styles.

• Up to 360mm radiator support
• Up to 140mm ATX PSU support
• M-ATX/Mini-ITX MB support
• Up to 168mm CPU cooler clearance
• Up to 358mm 4-slot GPU support
• Pre-installed with 2 slim fans
• Supports both horizontal and vertical layouts
• Up to 9 fans supported

Compact Design, Broad Compatibility

With a compact 21.3L volume, the B4-mATX delivers impressive hardware compatibility, supporting M-ATX motherboards, 360mm AIOs, 140mm ATX PSUS, and up to 358mm 4-slot GPUs.

Rotatable AC Power Connector

Designed for both horizontal and vertical configurations, the rotatable AC inlet adapts to your setup. Face it outward for convenient cable access, or rotate it inward in vertical mode to avoid clearance limitations.

Note: The power cable is pre-secured to prevent rubbing against the chassis when rotated. Leave the cable tie in place and position the cable before assembly.

Reversible Rear Fan Bracket

The rear fan bracket features a reversible design for greater layout flexibility. It can be installed outward to create more clearance for liquid cooling, or inward to position the fan closer to the CPU airflow path and improve CPU air-cooling performance by up to 1°C.

Note: The rear fan bracket supports standard 120mm fans only.

Recommended Liquid Cooling Configuration

The B4-mATX supports 360mm and 280mm radiators with up to 52mm total thickness.

360/280mm AIO Setup

• SFX PSU + M-ATX motherboard
• 3 x Bottom fans
• 2 x Top slim fans (pre-installed)

240mm AIO Setup

• 140mm ATX PSU + M-ATX motherboard
• 3 x Bottom fans
• 2 x Top slim fans (pre-installed)
• 1 x Rear fan

Note: Due to internal space limitations, fans must be installed outwards when using liquid cooling.

240mm AIO Installation Setup

• SFX PSU + M-ATX motherboard
• Bottom fans x3
• Front fan x1
• Rear fan x1
• Top slim fans x2 (pre-installed)

280mm AIO Installation Setup

• SFX PSU + M-ATX motherboard
• Bottom fans x3
• Rear fan x1 / Front fan x1
• Top slim fans x2 (pre-installed)

Note: Due to internal space limitations, fans need to be installed outside the chassis when installing an AIO liquid cooler.

Recommended Air Cooling Configuration

162mm Air Cooler Setup

• SFX PSU + M-ATX motherboard
• 3 x Bottom fans
• 1 x Side fan
• 1 x Rear fan
• 1 x Front slim fan
• 2 x Top slim fans (pre-installed; front fan flipped to intake)

168mm Air Cooler Setup

• 140mm ATX PSU + M-ATX motherboard
• 3 x Bottom fans
• 1 x Rear fan
• 2x Top slim fans (pre-installed; front fan flipped to intake)

Note: Due to internal space limitations, fans need to be installed outside the chassis when installing an AIO liquid cooler.

Flexible Cooling Configuration

• Top: 2 x 120mm slim fans (pre-installed)
• Side: 3 x 120mm fans / 2 x 140mm fans or 360mm / 280mm/240mm radiator
• Rear: 1 x 120mm fan
• Bottom: 3 x 120mm fans / 2 x 140mm fans
• Front: 1 x 120mm slim fan

(Note: The front slim fan is not supported with 360mm radiator or ATX PSU installation.)

• 360mm AIO x1
• 120mm Fans x9
• 140mm Fans x4

*Supports a maximum thickness of 15mm.

Note: To install three 120mm fans, the PCIe accessory below the PCIe slots must be removed.

Extra Intake, Better Cooling

Supports a 120 x 120 x 15mm slim front fan with an SFX PSU and GPU under 343mm long, helping improve intake airflow.

Pre-Installed 15mm Slim Fans, Flexible Airflow Design

Two pre-installed 120 x 120 x 15mm slim fans on the top provide enhanced cooling performance. Operating up to 1800 RPM, they are daisy-chained to reduce cable clutter.

• Size: 120 X 120 X 15mm
• Speed: 0~1800 ± 10% RPM
• Airflow: 64.2 CFM
• Static Pressure: 2.4mmH₂O
• Noise: 30.3dBA

Flexible GPU & Fan Support

Supports up to 358mm long 4-slot graphics cards. Bottom fan support varies by GPU thickness: 2.5-slot GPUs support 25mm fans, 3-slot GPUs support 15mm slim fans, and 3.5-slot or thicker GPUs do not support bottom fans.

Easy GPU Installation

The removable front fan bracket lets large graphics cards slide in from the front side of the chassis for a smoother installation process.

Pre-Installed GPU Anti-Sag Bracket

Built to handle GPUs up to 4 slots thick and 358mm long, the case comes equipped with a dedicated anti-sag bracket to ensure stability and prevent sagging.

Modular Design, Easier Installation

Tool-less removable panels offer quick and easy access for installation and cable routing, while a removable bottom dust filter helps maintain a clean system.

Removable Top Fan Bracket

The removable top fan bracket provides easier access for routing and managing CPU 8-pin cables, while also making it simpler to configure the front-top fan as intake for air-cooler setups.

Vertical AeroDeck (Optional Accessory)

In vertical layout, the Vertical AeroDeck enhances GPU cooling while maintaining a cohesive look with the case. It supports up to three 120mm or two 140mm fans, includes a PVC dust filter, and features tempered glass side panels to showcase fan side-frame lighting.

Note: Installation requires repositioning the I/O module.

Thermal Performance Test

Test Configuration (GPU: ROG Astral 5080)	Max / Average Temperature
Without Vertical AERODECK	68.6/66.5°C
With Vertical AERODECK (3 x 120mm fans at 1800 RPM)	64/61.9°C

Flexible Storage Support

Supports 1 x 2.5" SSD at the front, with space at the bottom for either 1 x 2.5" SSD or 1 x 3.5" HDD.

Note: Installing a 3.5" HDD on the bottom limits GPU thickness to 65mm and allows for only one 120mm bottom fan. With a 2.5" SSD installed, two 120mm bottom fans can be supported.

Accessible Connectivity

The I/O layout keeps essential ports easy to reach in both traditional and vertical layouts, with a high-speed USB Type-C port supporting up to 20Gbps transfer speeds.

Minimal Design, Multiple Styles

The B4-mATX offers a clean mesh panel for an airflow-focused look or a real wood panel for a warmer, refined setup. Both support front-to-back airflow, balancing cooling performance with a streamlined exterior.

Vertical Mode, Maximised Desk Space

The vertical layout improves desk space efficiency by up to 30%. Integrated rear feet allow quick and easy switching between different usage modes.

Easier Cable Management

Cable tie points around the PSU and top brackets help secure CPU 8-pin and PSU cables for a cleaner, more organised build.

1. Cable Clip & Tie Point

2. Cable Tie Point

In vertical mode, a removable bracket and rotatable cable guide work together to route cables cleanly through the bottom of the case.

Note: 52mm of total desk clearance is recommended for standard HDMI/DP cable routing. Longer connectors may require an adaptor.

In Collaboration with Dan Cases

Co-developed with Daniel Hansen of DAN Cases, the B4-mATX combines flexible modularity with LIAN LI's precision craftsmanship in a compact form.

PSU Hardware Compatibility

PSU Type Side Radiator GPU Length Rear Fan Front Fan (15mm slim fan) ATX PSU 240mm 358mm 120mmx1 / SFX PSU 240mm 343/358mm 120mmx1 120mmx1 SFX PSU 280mm 343/358mm / 120mmx1 SFX PSU 280mm 343/358mm 120mmx1 / SFX PSU 360mm 358mm / /

Note: When installing a 15mm-thick slim front fan, the maximum GPU length is limited to 343mm. The total thickness of the radiator and fan must not exceed 52mm.