Today we're looking at the Lian Li B4 mATX – a compact, 21.3-litre Micro-ATX case developed in collaboration with DAN Cases. Despite its small footprint, it supports Micro-ATX motherboards, graphics cards up to 358mm long, both ATX and SFX power supplies, and even a 360mm AIO. It also offers the choice of a mesh or real wood front panel, along with the option to run the case horizontally or vertically to better suit your setup. Lian Li is aiming to deliver the hardware compatibility of a much larger chassis in a compact SFF design. In this review, we'll find out if the B4 mATX can deliver on that promise, or not. Let's get into it.

Timestamps:

00:00 Introduction
00:58 Versions / Prices / Extras
01:51 Physical Dimensions / Front I/O
02:26 Removing panels
03:42 Cooling Support
06:25 GPU Anti Sag Bracket / GPU Support
07:25 Motherboard and CPU Air Cooler Support
08:22 Storage Compatibility
08:54 Back of the case
09:53 Left hand side of case
10:38 James thoughts on the layout
11:38 Accessories
12:22 Vertical AeroDeck
13:18 Thermal and Acoustic Performance Testing
15:11 Smoke Test
15:48 Thoughts on Installation
18:38 Closing Thoughts

Features:

• Compact 21.3-litre Micro-ATX design with support for Micro-ATX motherboards, graphics cards up to 358mm long, plus the option to position the case horizontally or vertically.
• Strong hardware compatibility including support for ATX or SFX power supplies, up to a 360mm side-mounted AIO with an SFX PSU, and CPU air coolers up to 162mm tall.
• Choice of mesh or real wood front panels combined with modular brackets, pre-installed slim fans and flexible cooling layouts designed to maximise performance in a compact chassis.

Specifications:

• Case Type: Micro ATX
• Dimensions (LxWxH): 420mm x 191mm x 288mm
• Materials: Steel, Wood (Walnut / Beech), Plastic
• Motherboard Support: Micro-ATX, Mini-ITX
• Reverse Connector motherboard support: No
• Expansion Slots: 4
• Storage bays: Front 2.5” SSD x 1, Bottom 3.5” HDD x 1 or 2.5” SSD x 1
• Max GPU Length: 358mm
• Max CPU Cooler Height: 162mm (168mm without side fan bracket)
• PSU Type: ATX/SFX
• Cable Routing Space: N/A
• Supplied Fans: 120 x 120 x 15mm (x2)
• Fan Support: 120mm x 2 (Top), 120mm x 1 (Front, With SFX PSU Only), 120mm x 3 / 140mm x 2 (L/H Side With SFX PSU), 120mm x 2 / 140mm x 2 (L/H Side With ATX PSU), 120mm x 1 (Rear), 120 mm x 3 / 140mm x 2 (Bottom)
• Radiator Support: Side 360mm (with SFX PSU), 240mm (With ATX PSU)
• Dust Filters: Bottom
• Font I/O: USB 3.0 Type A x 2, Power Button x 1, Audio x 1, USB 3.2 Type C x 1

Thermal Performance Testing

To simulate thermal demand, we run the Cinebench R23 multi-thread benchmark and 3DMark Speed Way stress test simultaneously in a loop for 30 minutes to load the system fully. This gives the CPU and GPU enough time to reach constant steady-state temperature. With this data, we can compare how the system handles the thermal demand and measure peak noise levels.

Thermal performance is measured with the case in various configurations, such as the default, with the tempered glass left-hand side panel removed and with the front panel removed to see how these configurations affect the CPU and GPU temperature. During testing, only stock case fans are used unless otherwise specified. All water pumps are set to maximum RPM and fans are set to a custom RPM curve by the Motherboard software/BIOS.

All temperature measurements are presented as Deltas – meaning the ambient temperature has been deducted from the CPU temperature, giving us a Delta. Data shown in the charts represents the average component temperature over the length of the test as measured by HWiNFO, and then the last 15 minutes of the data are calculated to get the average. The ambient temperature during thermal tests is between 19-20⁰C.

Test System Specification:

• CPU – AMD Ryzen 7 9800X3D
• Motherboard – Sapphire Nitro+ B850M WiFi
• Graphics Card – Gigabyte RTX 5080 Gaming OC
• Memory – 32GB (2 x 16GB modules) G.SKILL Trident Z5 Neo RGB DDR5-6000
• Storage – 1TB Corsair MP600 Elite PCIE Gen4 NVMe M.2 SSD
• CPU Cooler – Lian Li GA II Lite 360 (with Noctua A12x25 G2 Fans)
• Power Supply – Lian Li SP1000P SFX
• Case fans – Stock
• Chassis – Lian LI B4 mATX
• Operating System – Windows 11 24H2

Thermal Performance Overview

We test case thermals using a 360mm AIO as Intake at the side and with the case in several different fan configurations. The default configuration shown in the charts is with the side-mounted 360mm AIO cooler and 2 x 120 mm x 15 mm top exhaust fans and with all case panels installed.

Thermal performance good overall, with the B4 mATX delivering consistent CPU and GPU temperatures across all four test configurations. The default AIO setup performs well, but removing the top fans results in a increase to both CPU and GPU temperatures, so those exhaust fans play an important role in the case's airflow design.

Running the case vertically with the optional AeroDeck produces the best GPU temperature while matching the lowest CPU result, so the additional cost could be a worthwhile improvement to graphics cooling. most interestingly, removing the top, front and side panels offers no benefit over the AeroDeck configuration, indicating that the B4 mATX's airflow is well optimised in its standard configuration.

Noise Output

Acoustically, the B4 mATX offers a balance between cooling performance and noise, with only slight variation between the different test configurations. The default setup produces the same idle noise level as both the AeroDeck and top fan removed configurations, while load noise remains close across test configurations.

The vertical AeroDeck configuration is slightly quieter under load due to the lower GPU temperature and fan speed, but the differences are small enough that they're unlikely to be too noticeable in day-to-day use.

Closing Thoughts

Considering its compact dimensions, Lian Li has packed an impressive amount of hardware support into the B4 mATX including large 4 slot graphics cards, ATX power supplies and up to a 360mm AIO, making it more versatile than some small form factor chassis in this price bracket. There’s a good balance between compact dimensions and practicality, giving enthusiasts flexibility without forcing them into buying expensive SFX power supplies or low-profile cooling solutions.

Thermal performance is respectable too. While the B4 mATX isn't class-leading in terms of cooling, it does an adequate job for a chassis of this size and should have no trouble handling high-performance gaming hardware when configured correctly. Combined with the excellent build quality we've come to expect from Lian Li, the chassis feels well engineered, with premium materials and a solid build for the MSRP asking price.

That said, the B4 mATX isn't without compromise. As with many compact cases, component compatibility depends heavily on the exact hardware combination you choose. Installing larger graphics cards, radiators or longer power supplies can have a knock-on effect elsewhere in the build, so planning your component selection is essential. Cable management is also more challenging than it should be, with limited routing space making it difficult to achieve a clean build, while some cables can easily get in the way of the top fans if you're not careful during assembly too.

There are also a couple of smaller details that could have been better executed. The included GPU anti-sag bracket is a useful feature, but its compatibility with some graphics cards is limited. None of these issues are deal breakers, it’s still a very capable compact chassis.

Overall though, the Lian Li B4 mATX delivers a solid combination of build quality, hardware compatibility and sensible pricing, making it an easy case to recommend for anyone wanting to build a powerful mATX gaming system without taking up too much desk space.

The Lian Li B4 mATX is available to purchase now from Scan priced at £73.99 HERE.

Pros: 

• Can support high-end hardware depending on configuration.
• For a compact case, cooling support is good.
• Build quality is excellent.

Cons:

• GPU anti-sag arm is incompatible with some graphics cards.
• Hardware compromises depending on configurations.
• Cable routing is awkward and some cables can get trapped in fans.

KitGuru says: For a small case, the B4 mATX packs in some good features but there are some hardware compromises depending on what setup you run though this is to be expected from such a compact mATX case.

The Lian Li B4-mATX measures a mere 420 x 191 x 288mm (16.5 x 7.5 x 11") so only Mini-ITX and M-ATX motherboards need apply.  It ships with a pair of 120mm…

Lian Li has announced the B4-mATX, a 21.3-litre small form factor chassis co-developed with Dan Cases. Now available, the compact enclosure supports mATX motherboards and can be oriented either horizontally as a desktop unit or vertically as a space-saving tower.

The B4 case rotates 90º into a vertical orientation, reducing the desktop footprint by 30%. A rotatable AC inlet adjusts to both configurations, turning outward for cable access or inward to absorb excess length. A swivelling cable bracket below the PCIe slots keeps the rear I/O flush against the case, offering up to 52mm of connector clearance. Lian Li provides front-panel options in mesh or real wood (walnut or beech) across black or white finishes.

The chassis ships with two pre-installed 120x120x15mm slim exhaust fans on a removable bracket. It supports graphics cards up to 358mm across four expansion slots, and CPU coolers up to 162mm tall, or 168mm tall with the side bracket removed. Dedicated brackets fit an SFX or a 140mm ATX power supply. Using an SFX unit enables side radiator compatibility up to 360mm, while an ATX model limits it to 240mm. Drive options support a 3.5-inch HDD or 2.5-inch SSD at the bottom, plus a 2.5-inch SSD at the front.

An optional B4-mATX Vertical AeroDeck accessory adds tempered glass panels and expands capacity by up to three 120mm or two 140mm fans. Pricing starts at $69.99/€69.99 for the black Mesh version and ranges up to $89.99/€89.99 for the white Wood model. The AeroDeck costs $29.99/€29.99.

KitGuru says: The dual-orientation design, relatively low price, and inclusion of real wood aesthetic options make the B4-mATX a highly versatile entry into the SFF case market.

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.

Lian Li has officially announced the Vector V150 INF, a compact mini-tower chassis designed for enthusiasts who want to blend high-performance cooling with a striking visual presentation. Building on the foundation of the Vector V100 MINI, this new iteration introduces “Infinity” aesthetic elements, including an infinity-mirror front panel.

The defining feature of the Vector V150 INF (via Guru3D) is its lighting system. Unlike the standard mesh or glass panels found on many mATX cases, the V150 INF uses infinity-reflection elements on its front panel. To complete the look, Lian Li includes three pre-installed Infinity ARGB/PWM fans: two 140mm fans at the front and a 120mm exhaust fan at the rear, all featuring infinity-mirror centres.

Image credit: Guru3D

The Vector V150 INF supports Micro-ATX and Mini-ITX motherboards, including the increasingly popular back-connect (BTF) designs. The chassis accommodates graphics cards up to 400mm in length and supports air coolers up to 163.5mm in height. For cooling components, the top panel can accommodate a 360mm radiator, while the side and bottom panels provide additional fan mounting points for a flexible layout.

The front I/O panel offers two USB-C 3.2 Gen 2 ports, one USB-A 3.2 Gen 1 port, and an HD-audio jack. Storage support includes slots for two 2.5/3.5-inch drives, though this is reduced to a single bay if using a long power supply up to 200mm. The case is scheduled for release later this month, with initial availability confirmed for the Japanese market. Pricing is expected to be around £70.

KitGuru says: Considering its looks, features, and price, it seems Lian Li has another winner with the V150 INF.

Geometric Future has officially expanded its “Model” series with the introduction of the Model 3. Drawing clear design inspiration from the larger Model 5, this latest entry adopts a more compact footprint, therefore changing compatibility with components.

Measuring 235 x 440 x 400mm, the Model 3 (via ITHome) adopts an “aquarium” aesthetic, with a dual-panel glass front that provides an unobstructed view of the internal components. The case is launching in a variety of bold colourways, including yellow, grey, white, and green. Interestingly, the colour choice isn't just limited to the panels, as the power supply shroud and case feet are also colour-matched to create a cohesive look.

Internally, Geometric Future has opted for an unconventional front-side mounting position for the power supply. While this allows for more clearance elsewhere, it limits PSU depth to 160mm. Despite its smaller stature, it still offers ample room for core components, supporting graphics cards up to 435mm in length and CPU coolers up to 175mm in height. However, motherboard support is strictly limited to Micro-ATX and Mini-ITX form factors, and those hoping for “back-connect” BTF motherboard compatibility will be disappointed to find it missing here.

Cooling capacity remains flexible as long as you stick to 120mm fans. The Model 3 can house up to eight 120mm units, whereas 140mm support is restricted to just four mounts. For those leaning toward liquid cooling, the top panel supports a 360mm radiator. The chassis also includes several QoL features that punch above its weight class, such as a bottom dust filter accessible from the side, an integrated GPU anti-sag bracket, and pre-placed Velcro straps for cable management.

KitGuru says: While the front-mounted PSU and Micro-ATX form factor might turn some off, the Model 3 offers a clean “aquarium” look for those who want the Model 5 aesthetic with a smaller footprint.

Jonsbo is expanding its case lineup with the launch of the D33 and its wood-accented sibling, the D33 Wood. These Micro-ATX cases are built for enthusiasts who want a “furniture look” without sacrificing the cooling potential required for modern high-end hardware.

Available in black and white across both variants, the D33 series features a compact footprint of 455 x 238.2 x 368.4mm. The standard D33 features a plastic front panel defined by bevelled vertical bars. For the D33 Wood, Jonsbo swaps these for genuine wood slats, utilising a light oak-like wood for the white chassis and a darker walnut-toned wood for the black version. While the wood variant uses straight bars rather than bevelled edges, both models maintain a clean, integrated I/O panel that includes a USB-C port, two USB-A 3.0 ports, and a power button.

The D33 natively supports motherboards with rear-mounted connectors, such as the MSI Project Zero or Asus BTF series. To accommodate these boards, Jonsbo has engineered a large, component-free zone behind the motherboard tray for routing. This focus on a clean interior does come with a slight trade-off in storage, as the case relies on a single bracket behind the CPU backplate that can hold two 2.5-inch or 3.5-inch drives. However, this layout leaves the bottom of the chassis open for three 120mm intake fans and two 120 or 140mm fans on the front, depending on whether you're using an ATX or an SFX PSU.

Regarding cooling, the cases use a “sandwich” mounting system for top-mounted radiators. Rather than bolting the cooling kit directly to the chassis frame, the fans, mounting plate, and radiator are layered together into a single module that then attaches to the top panel. While this requires a bit more assembly time than a traditional mount, it allows the D33 to support a full 360mm radiator in a Micro-ATX frame. For those who prefer air cooling, the case offers 172 mm of clearance for CPU towers. Lastly, there's space for PSUs up to 160 mm long and cards up to 435 mm long.

KitGuru says: If you're planning to downsize your build, the D33 looks like a potentially good option for a compact case.