Description

Lian Li B4-mATX Mesh SFF PC Case: A 21.3-Litre Mesh Case That Still Takes a Full-Size Graphics Card

Introduction

The Lian Li B4-mATX Mesh is a 21.3-litre small form factor case for Micro-ATX and Mini-ITX boards. It is wrapped in steel mesh on every visible side, ships with two slim 120mm fans in the roof, and still makes room for a 358mm, four-slot graphics card and a normal ATX power supply. This write-up looks at what the layout means for a real build, where its limits are, and who it suits.

1. Size and Layout

At 420 x 191 x 288mm the B4 sits on a desk more like a shoebox than a tower. It is laid out horizontally, with the motherboard and graphics card side by side, which is why a long four-slot card fits in a case this small. A 120mm slim fan bracket on the side and the roof fans keep the main chamber fed with fresh air.

2. Graphics Card and CPU Cooler Clearance

Cards up to 358mm long and four slots thick fit, which covers most current high-end graphics cards. Tower air coolers up to 159mm tall fit with the side fan bracket in place, or 165mm with it removed, so a mid-size single-tower cooler is the safe choice if you are not using liquid cooling.

3. Power Supply Options

The B4 takes an ATX power supply up to 140mm long, or an SFX unit. That matters for cost: you can reuse a standard ATX PSU instead of buying a more expensive SFX model. A short 140mm ATX unit such as the Lian Li SX Platinum series is a clean match.

4. Liquid Cooling

Radiator support depends on the PSU you choose. With an SFX power supply, the side mount takes a 360mm, 280mm or 240mm radiator. With an ATX power supply in place, the side mount is limited to a 240mm radiator. Plan the PSU and cooler together before ordering.

5. Airflow and Fans

Two 120 x 120 x 15mm slim fans come pre-installed in the top. You can add up to three 120mm or two 140mm fans on the bottom, one 120mm at the rear, and side fans depending on the PSU. A magnetic dust filter covers the bottom intake.

6. Storage and Front I/O

Storage is kept minimal for the size: one 2.5-inch SSD at the front, and one 3.5-inch HDD or 2.5-inch SSD at the bottom, so most builds will rely on M.2 drives. The front panel has a USB 3.2 Type-C port, two USB 3.0 Type-A ports, an audio jack and the power button.

7. Who It Is Best Suited For

The B4 suits anyone who wants a full-power desktop with a strong graphics card but has limited desk space, and anyone building a compact living-room or office machine that should still be easy to work in. It is less suited to builds that need several hard drives or a 360mm radiator alongside an ATX power supply.

Conclusion

The Lian Li B4-mATX Mesh fits a large graphics card, a standard ATX power supply and a Micro-ATX board into 21.3 litres, with mesh on all sides and two fans included. Plan the PSU and cooler pairing first, and it makes a very capable small desktop.

Frequently Asked Questions

Does the B4-mATX support ATX motherboards?

No. It supports Micro-ATX and Mini-ITX motherboards only. Back-connect motherboards are not supported.

Can I use a 360mm AIO with an ATX power supply?

No. A 360mm radiator fits on the side only when you use an SFX power supply. With an ATX power supply, the side mount takes a 240mm radiator.

How long can the graphics card be?

Up to 358mm long and up to four slots thick.

Which fans are included?

Two 120 x 120 x 15mm slim fans are pre-installed in the top panel.

Does it have USB Type-C on the front?

Yes, one USB 3.2 Type-C port plus two USB 3.0 Type-A ports and an audio jack.

What warranty does it come with?

It comes with a 1-year warranty from Cores & Threads.