Lian Li has unveiled the new B4-mATX, a compact 21.3-liter PC case developed together with DAN Cases and aimed at small-form-factor enthusiasts looking for strong hardware support without going full ITX. The big update is that the new case supports both horizontal and vertical orientations, allowing users to switch between a traditional desktop layout or a tower-style setup that takes up around 30 percent less desk space, according to Lian Li.
Despite its relatively small footprint, the B4-mATX still supports Micro-ATX motherboards, graphics cards up to 358 mm long, CPU air coolers up to 162 mm tall, and both ATX and SFX power supplies. The chassis comes with two pre-installed 120 mm slim fans mounted on a removable exhaust bracket. Users running air cooling setups can also flip the front fan into an intake configuration for improved airflow. When it comes to cooling, the new B4-mATX is surprisingly flexible for its size, as with an SFX power supply installed, the case can handle radiators up to 360 mm on the side, while ATX PSU users still get support for up to 240 mm radiators. Lian Li also included a reversible rear fan bracket that can either improve airflow for tower coolers or create additional space for AIO tubing and radiators.
The B4-mATX is available with either a mesh front panel or a real wood finish using walnut or beech accents. Both versions come in black or white color options. Lian Li is also offering an optional Vertical AeroDeck accessory designed specifically for vertical builds. The add-on expands cooling capacity with support for up to three 120 mm fans or two 140 mm fans while adding tempered glass side panels and direct airflow toward the GPU. Connectivity includes two USB 3.0 Type-A ports, one USB Type-C port, and audio jacks on the front panel.
The new Lian Li B4-mATX PC case launches on June 26 with pricing starting at $69.99 for the Mesh Black version and going up to $89.99 for the Wood White model. The optional AeroDeck accessory will sell separately for $29.99.
