Lian Li B4 Offers Big Features in a Small PC Case

Lian Li has officially introduced the new Lian Li B4 mATX chassis, a compact small form factor case developed in partnership with DAN Cases. Despite its small 21.3-liter size, the case offers impressive hardware support and flexible installation options for PC builders looking to save space without sacrificing performance.

One of the biggest highlights of the Lian Li B4 mATX is its dual-orientation design. Users can place the case horizontally like a traditional desktop system or rotate it into a vertical tower layout. According to Lian Li, the vertical setup reduces desk space usage by around 30%, making it an attractive option for users with limited workspace.

The company has also designed the case with practical cable management features. A rotatable AC power inlet adjusts to different orientations, while a movable cable bracket helps keep cables neat and organized when the case is used vertically. Buyers can choose between a perforated mesh front panel for better airflow or a premium real wood finish available in walnut or beech styles. Both options are offered in black and white color variants.

The Lian Li B4 mATX comes with two pre-installed slim 120 mm fans that work as exhausts out of the box. Builders can easily customize airflow depending on their cooling setup. The chassis supports both ATX and SFX power supplies through dedicated mounting brackets, providing greater flexibility for different builds.

Cooling support is another strong point of the new chassis. Systems using an SFX power supply can install radiators up to 360 mm on the side, while builds using a 140 mm ATX power supply support radiators up to 240 mm. The rear fan bracket can also be repositioned to improve airflow for air coolers or create additional space for liquid cooling solutions.

Even with its compact footprint, the Lian Li B4 mATX can accommodate powerful hardware. The case supports graphics cards up to 358 mm long across four expansion slots and CPU air coolers up to 162 mm tall. Users can gain even more cooler clearance by removing the side fan bracket. A built-in adjustable anti-sag bracket is also included to help support larger graphics cards.

Storage options include support for one 3.5-inch hard drive or 2.5-inch SSD at the bottom of the case, along with an additional 2.5-inch SSD mounting position at the front.

For users seeking improved GPU cooling, Lian Li is also offering the optional B4 mATX Vertical AeroDeck accessory. Designed specifically for vertical builds, the AeroDeck adds extra airflow directly to the graphics card and supports up to three 120 mm fans or two 140 mm fans. It also features tempered glass side panels and a magnetic dust filter while matching the wood styling available on the main chassis.

Lian Li B4 mATX case pricing and availability

The Lian Li B4 mATX and the optional Vertical AeroDeck became available on June 26, 2026. Pricing starts at $69.99 for the Mesh Black version, while the Wood White model is priced at $89.99. The Vertical AeroDeck accessory is available separately for $29.99.