Micro ATX cases worth buying

The best micro ATX case in the UK is the Lian Li A3-mATX at £73.99 on Amazon UK at the time of writing (October 2026). Lian Li fits a 415 mm graphics card, a 165 mm CPU cooler, a 360 mm radiator and a full ATX power supply into 26.3 litres, less than half the volume of an ATX mid tower such as the 57.7-litre Lian Li Lancool 217. The Corsair 2500X at £98.62 is the best dual-chamber showcase, and the Phanteks XT M3 at £67.89 is the best value because three fans come in the box. The Lian Li O11 Vision-M at £66.12 is the cheapest way into a dual-chamber glass build.

These picks sit under Compare Electronic's Best PC case UK 2026 guide, and every size class is compared in PC case sizes explained. This guide adds what a micro ATX case gives up against a mid tower, what the boards cost, and the checks that stop a build failing.

What is the best micro ATX case?

The Lian Li A3-mATX is the best micro ATX case for most builds because it is the smallest case here that still takes full-size parts. Its 26.3 litres compares with 40.0 litres for the Phanteks XT M3, 45.6 litres for the Lian Li O11 Vision-M, 47.9 litres for the ASUS Prime AP202 ARGB and 53.6 litres for the Corsair 2500X, Compare Electronic's calculations from each maker's external dimensions.

Micro ATX does not mean small by default. The Corsair 2500X takes a micro ATX board, but at 469 x 304 x 376 mm it is wider than many ATX mid towers, because its power supply sits in a second chamber behind the motherboard. Some Amazon UK listings even call the micro ATX O11 Vision-M a mid tower. Buyers shopping for a small gaming PC case should sort by litres first and board size second.

1. Lian Li A3-mATX - best micro ATX case

The Lian Li A3-mATX costs £73.99 on Amazon UK at the time of writing (October 2026) in the black Wood Edition, which lays a walnut-trim front over steel mesh. DAN Cases designed it and Lian Li builds it. Lian Li lists a 415 mm, 4-slot graphics card limit, a 165 mm CPU cooler limit and ten 120 mm fan mounts, and the power supply can sit at the front or the side in ATX, SFX or SFX-L sizes up to 220 mm. The wood front costs £46.00 less here than on the Fractal Design North mid tower at £119.99.

Lian Li documents the compromises itself. A 25 mm fan in the bottom position limits the graphics card to 61 mm, about three slots, and a bottom radiator with fans leaves no room for a graphics card at all, so radiators belong on the top or side. No fans come in the box. The Wood Edition has mesh side panels; Lian Li sells a tempered glass side panel, listed at £16.68 on Amazon UK, and a vertical GPU kit with a 150 mm PCIe 4.0 riser.

2. Corsair 2500X - best dual-chamber showcase

The Corsair 2500X costs £98.62 on Amazon UK at the time of writing (October 2026) for the black version without fans. It is a dual-chamber case: the motherboard and graphics card sit behind panoramic glass in the main chamber, and the power supply and cables sit in a second chamber behind it, so the window shows only components. Corsair lists support for reverse-connector motherboards such as ASUS BTF, MSI Project Zero and Gigabyte Project Stealth, which move the cable headers to the back of the board.

Radiator capacity is the highest here. Corsair lists 360 mm radiators at the top and the bottom, a 240 mm radiator on the side and nine fan mounts, with a 400 mm graphics card limit and a 180 mm cooler limit. The costs are size and fans: at 53.6 litres by Compare Electronic's calculation, the 2500X is twice the volume of the Lian Li A3-mATX, this listing has no fans, and the vertical GPU mount needs a kit sold separately.

3. Phanteks XT M3 - best value with three fans

The Phanteks XT M3 costs £67.89 on Amazon UK at the time of writing (October 2026) for the white version with three 120 mm fans, the cheapest pick here with three fans in the box. Phanteks lists a 430 mm graphics card limit with the front fans removed, a 175 mm CPU cooler limit, a 360 mm top radiator and nine 120 mm fan mounts, three of them under the graphics card. The front USB-C port runs at 20Gbps, twice the speed of the Corsair 2500X's port.

The XT M3 has one hard limit to check before ordering: Phanteks mounts the power supply at the front and caps its length at 150 mm. The ATX design guide's reference depth is 140 mm, but many high-wattage units are longer, so check the power supply's spec sheet. Phanteks lists no vertical GPU support, and the top is the only radiator position.

4. ASUS Prime AP202 ARGB - best with RGB fans included

The ASUS Prime AP202 ARGB costs £99.99 on Amazon UK at the time of writing (October 2026) in black. ASUS wraps one curved tempered glass panel from the front round to the side and fits three 120 mm ARGB fans, two on the side and one at the rear. It takes a 420 mm graphics card, a 175 mm CPU cooler, a 360 mm top radiator and an ATX power supply up to 200 mm.

Against the Corsair 2500X, the AP202 costs £1.37 more but includes three ARGB fans, which the fanless 2500X listing lacks. The trade-off is cooling headroom: ASUS lists six fan mounts and one radiator position, against nine mounts and four radiator positions on the 2500X.

5. Lian Li O11 Vision-M - best cheap showcase case

The Lian Li O11 Vision-M costs £66.12 on Amazon UK at the time of writing (October 2026) in black, the cheapest case in this guide. It is a dual-chamber showcase like the Corsair 2500X, with 4 mm and 3 mm tempered glass on three sides, for £32.50 less. Lian Li lists a 410 mm graphics card limit, a 162 mm CPU cooler limit, a 360 mm top radiator and 13 fan mounts, the most of any pick, with one 140 mm fan pre-installed in the second chamber.

The Amazon UK title calls it a mid tower and back-connect ready, but Lian Li's own spec page lists micro ATX and Mini-ITX boards only and Back-Connect as No, so buyers with an ASUS BTF or MSI Project Zero board should choose the Corsair 2500X or Phanteks XT M3. The power supply must be ATX and under 182 mm, and only the top takes a radiator on this version.

What do you give up with a micro ATX case instead of a mid tower?

Very little on the case side. Compare Electronic matched two micro ATX picks against an ATX mid tower from the same brand, and the micro ATX case fits the longer graphics card in both pairs. The real losses are power supply length in the Phanteks XT M3, radiator positions, and fans in the box.

The Lian Li A3-mATX fits a graphics card 35 mm longer than the Lian Li Lancool 217 in less than half the volume, and costs £36.00 less. The Phanteks XT M3 saves £9.10 against the Phanteks XT Pro Ultra but gives up 120 mm of power supply length and the front and rear radiator positions. The full mid tower shortlist is in Best mid tower PC case UK 2026.

The bigger loss sits on the motherboard. The micro ATX standard caps boards at 244 x 244 mm with up to four expansion slots, against 305 x 244 mm and seven slots for ATX, so micro ATX boards usually carry fewer PCIe and M.2 slots. A gaming PC with one graphics card and two SSDs rarely needs more.

Are micro ATX motherboards cheaper than ATX?

Usually at the bottom of the range, not always. On Amazon UK at the time of writing (October 2026), the MSI B850M Gaming Plus WiFi6E micro ATX board costs £115.00 against £124.70 for the ATX MSI B850 Gaming Plus WiFi6E, a £9.70 saving. Gigabyte's Eagle pair runs the other way: the micro ATX B850M Eagle WiFi6E costs £149.99 and the ATX B850 Eagle WiFi6E £139.00.

Mini-ITX is where the premium sits. The ASUS ROG Strix B850-I Gaming WiFi costs £246.98, more than twice the cheapest B850 micro ATX board, which is why micro ATX is the value route to a small PC. Board picks by budget are in Best motherboard for gaming UK 2026.

Is a micro ATX case the best small gaming PC case?

Yes, for most buyers. A micro ATX case such as the 26.3-litre Lian Li A3-mATX takes a standard ATX power supply, a tower cooler and a 415 mm graphics card, and B850 micro ATX boards start at £115.00. Mini-ITX cases go smaller, from 10.4 litres for the Fractal Design Terra, but need an SFX power supply, a low-profile cooler or an AIO, and a board costing about twice as much; those trade-offs are in Best mini ITX case UK 2026.

Six checks catch most failed micro ATX builds. Compare Electronic's list below comes from the limits each maker publishes.

Every pick clears the 304 mm length of Nvidia's RTX 5090 Founders Edition with at least 96 mm to spare, so graphics card length rarely decides a micro ATX case. Graphics card choices are in Best graphics card UK 2026, and the cost of building against buying is in Build vs buy a gaming PC UK 2026.

Best micro ATX case UK 2026 compared

The Lian Li A3-mATX is the smallest, the Corsair 2500X has the most radiator room, the Lian Li O11 Vision-M is the cheapest, and the Phanteks XT M3 and ASUS Prime AP202 ARGB are the two with three fans in the box.

Verdict

The Lian Li A3-mATX at £73.99 is the best micro ATX case in the UK: 26.3 litres, a 415 mm graphics card, a 360 mm radiator and a full ATX power supply, for less than most mid towers. The Corsair 2500X at £98.62 is the pick for a glass showcase with two 360 mm radiators, the Phanteks XT M3 at £67.89 is the value pick with three fans, and the ASUS Prime AP202 ARGB at £99.99 suits a buyer who wants RGB fans without extra purchases. The Lian Li O11 Vision-M at £66.12 is the cheapest glass showcase, for builders without a back-connect board.

A micro ATX case gives up motherboard slots, not graphics card room. The wider shortlist across every size is in Best PC case UK 2026.