Micro-ATX has quietly become the form factor to watch in 2026. NZXT’s H3 Flow — a from-scratch 2025 redesign, not a rebadge of the old H3 — is showing up on best-case lists from PCGamer and PCPerspective for undercutting full ATX mid-towers on price while still swallowing full-length GPUs. Lian Li’s A3-mATX, born out of the DAN Cases collaboration, is pulling off something similar from the small-form-factor side: 415mm of GPU clearance and 360mm radiator support in a 26.3-liter box that GamersNexus has benchmarked against much larger cases. You no longer have to choose between a compact footprint and room for flagship hardware.
| Spec | NZXT H3 Flow 8.9/10 | Lian Li A3-mATX Unavailable 8.8/10 | DeepCool CH370 Unavailable 8.3/10 | Fractal Design Pop Mini Air RGB Unavailable 8.6/10 | Jonsbo D30 Unavailable 8.5/10 |
|---|---|---|---|---|---|
| formFactor | mATX Mid-Tower | mATX Open-Frame SFF | mATX Mid-Tower | mATX Mid-Tower | mATX / DTX Tower |
| motherboard | mATX / Mini-ITX | mATX / Mini-ITX | mATX / Mini-ITX | mATX / Mini-ITX | mATX / DTX / Mini-ITX |
| includedFans | 1× 120mm rear | None | 1× 120mm rear | 3× 120mm Aspect RGB | None |
| radSupport | Front 280mm / Top 240mm | 360mm (top, bottom, or left) | Front 360mm / Top 240mm / Rear 120mm | Front 240mm / Top 240mm / Rear 120mm | 240mm (top or bottom) |
| gpuClearance | 352mm (with front fans) | 415mm | 320mm | 365mm (with front fan) | 355mm (305mm with large PSU) |
| cpuClearance | 170mm | 165mm | 165mm | 170mm | 168mm |
| Rating | 8.9/10 | 8.8/10 | 8.3/10 | 8.6/10 | 8.5/10 |
Prices change daily — tap Check Price for the current Amazon price.
Prices change daily — tap Check Price for the current Amazon price.
Quick Picks
- Best Overall: NZXT H3 Flow — 352mm of GPU clearance and back-connect motherboard support for $56.99, the strongest all-around value here.
- Best Compact Build: Lian Li A3-mATX — 415mm GPU clearance and 360mm radiator support in a 26.3-liter chassis that rivals full ATX towers.
- Best Budget: DeepCool CH370 — 360mm front radiator support at $69.99, the cheapest way into serious liquid cooling on this list.
Buying Guide
Why mATX Instead of ATX or Mini-ITX
Micro-ATX sits in the middle for a reason. Full ATX motherboards and cases give you more PCIe slots and RAM banks than most gaming builds actually use, while Mini-ITX cases like those in our best Mini-ITX cases roundup force compromises on radiator size and cable routing that frustrate first-time small-form-factor builders. mATX boards — covered in our best mATX motherboards guide — keep two or three expansion slots and both memory channels while dropping the extra length of a full ATX board. If you’re unsure which form factor fits your plans, our ATX vs mATX vs ITX breakdown covers the trade-offs in more depth.
GPU Clearance Varies More Than You’d Expect
The five cases here span a 95mm range in GPU clearance — 320mm on the DeepCool CH370 up to 415mm on the Lian Li A3-mATX. That gap matters: a reference RTX 5090 Founders Edition measures 336mm, which already exceeds the CH370’s limit, while triple-fan AIB variants from ASUS and Gigabyte can run past 380mm and rule out three of the five cases outright. Measure your card — or the card you’re planning to buy — against the exact spec before ordering a case.
Radiator Support Isn’t Uniform Across mATX Cases
Only the NZXT H3 Flow (280mm front) and DeepCool CH370 (360mm front) support anything beyond a 240mm front radiator, and only the Lian Li A3-mATX supports a full 360mm loop, spread across its top, bottom, or left panel. The Fractal Pop Mini Air RGB and Jonsbo D30 both cap out at 240mm, front or top. If a 360mm AIO is part of your plan, the A3-mATX or CH370 are the only two cases on this list that fit it without compromise.
Fans Included vs. Fans You’ll Buy
Two of these five cases — the Lian Li A3-mATX and Jonsbo D30 — ship with zero fans, which is standard for cases built around premium materials and clean aesthetics rather than out-of-box completeness. Budget $30–40 for two or three intake fans on either. The Fractal Pop Mini Air RGB is the only case here that arrives fully populated with three fans, while the H3 Flow and CH370 each include just one rear exhaust fan and expect you to add front intake yourself.
Motherboard Compatibility Beyond Standard mATX
The Jonsbo D30 is the only case on this list that also supports DTX boards, a less common form factor between Mini-ITX and mATX that a handful of enthusiast board makers still produce. If you’re building around a standard mATX board, all five cases apply equally; DTX support is a bonus rather than a requirement for most builders.
Detailed Reviews
NZXT H3 Flow — Best Overall
The NZXT H3 Flow is a ground-up 2025 redesign, not a refresh of the original H3, and it shows in the numbers. At 400 × 225 × 389mm, it’s genuinely compact, but it still clears 352mm GPUs with front fans installed and 377mm without — enough room for the vast majority of current cards, including most triple-fan AIB designs. That’s a wider clearance window than three of the four other cases on this list, despite the H3 Flow undercutting all of them on price.
Back-connect motherboard support is the standout feature. On a compatible mATX board, power and data cables route behind the motherboard tray instead of across the front, producing a noticeably cleaner build than the cable routing on the CH370 or D30. NZXT also rates the case for up to seven total fans, so there’s real room to grow the cooling setup later rather than hitting a hard ceiling on day one.
The trade-off is that only one 120mm fan — mounted at the rear — comes in the box. Filling the front with two or three more fans is close to mandatory for a build that relies on active airflow rather than passive convection, and that adds $30–45 to the effective price. The 240mm top radiator cap is also a real limit: if your plan involves a 360mm loop, it has to go in the front, and NZXT doesn’t give you a second location to split it across.
Best for: Builders who want the widest GPU compatibility and the cleanest cable routing at the lowest price on this list, and don’t mind adding fans themselves.
Lian Li A3-mATX — Best Compact Build
Lian Li A3-mATX
The Lian Li A3-mATX grew out of Lian Li’s collaboration with DAN Cases, and it inherits that lineage’s core trick: fitting genuinely high-end hardware into a genuinely small footprint. At just 26.3 liters, it supports 415mm GPUs and 360mm radiators across three different mounting locations — top, bottom, or left panel — a combination that GamersNexus’s benchmarks confirm outperforms cases twice its size on thermal headroom for flagship CPU and GPU pairings.
Build quality is the other reason it earns a spot here. The 1.0mm SECC steel frame paired with brushed aluminum panels feels distinctly more rigid than the thinner steel used in the CH370 or the H3 Flow, and it shows in how the panels sit and how little flex there is in the frame during a build. For builders who’ve been frustrated by flimsy panels on cheaper SFF-adjacent cases, this is a meaningful upgrade.
None of that comes with fans in the box — the A3-mATX ships completely empty on the cooling front, so plan on $30–40 for two intake fans before it’s ready to run. And the headline 415mm GPU spec has an asterisk: it assumes a thin 25mm front fan. Swap in a thicker 30mm fan like a Noctua NF-A12x25, and clearance drops by roughly 5mm — enough to exclude some of the longest triple-fan cards on the market, like the ASUS ROG Strix RTX 4090 OC at 437mm.
Best for: Builders who want the smallest possible footprint without sacrificing GPU length or radiator size, and who don’t mind sourcing their own fans.
DeepCool CH370 — Best Budget
DeepCool CH370
The DeepCool CH370 wins on a single number: 360mm of front radiator support for $69.99, which no other case on this list matches at anywhere close to the price. That’s paired with 240mm top and 120mm rear radiator mounts, giving it the most flexible cooling layout here if a big front-mounted AIO is the plan.
Beyond the radiator support, the CH370 punches above its price with details that usually show up on pricier cases — a magnetic tempered glass side panel that doesn’t require tools to remove, and a built-in headphone stand molded into the top panel. The 165mm CPU cooler clearance is also generous enough to fit the Noctua NH-D15 and nearly every other tower air cooler on the market without a fitment check.
The compromise is GPU clearance. At 320mm, the CH370 is the tightest case on this list — a reference RTX 5090 Founders Edition at 336mm won’t fit, and neither will most current mid-range cards with factory triple-fan coolers. This is a case built around radiator flexibility first and GPU length second; measure your card before buying.
Best for: Builders prioritizing front-radiator liquid cooling on a budget, running a GPU no longer than roughly 315–320mm.
Fractal Design Pop Mini Air RGB — Best Build Quality
Fractal Design Pop Mini Air RGB
The Fractal Design Pop Mini Air RGB is the only case on this list that’s genuinely ready to build in the moment it arrives. Three pre-installed 120mm Aspect RGB fans handle front intake without any aftermarket purchase, a real differentiator against the H3 Flow and CH370, which each include just one fan and expect the buyer to fill out the rest.
Fractal’s cable management design is also a step above the competition here. Velcro straps come pre-mounted at key routing points, pass-through holes are cut larger than necessary rather than just large enough, and more than a dozen tie-down points give builders room to route cables cleanly without buying extra zip-tie mounts. Combined with a 170mm CPU cooler clearance — tied with the H3 Flow for the tallest on this list — it’s an easy case to build a tidy system in.
At $99.99, it’s priced closer to a full ATX mid-tower than a budget mATX case, and the 240mm radiator cap on both the front and top panels means a 360mm AIO doesn’t fit anywhere in this chassis — a real limitation next to the A3-mATX or CH370’s front-mount 360mm support.
Best for: Builders who want a fully populated, RGB-lit case straight out of the box and don’t need more than a 240mm radiator.
Jonsbo D30 — Best Premium Design
Jonsbo D30
The Jonsbo D30 stands apart visually from the other four cases here. Where the H3 Flow, CH370, and Pop Mini Air lean on mesh panels and exposed steel, the D30 pairs an aluminum front and top panel with a tempered glass side window for a noticeably more minimalist, premium look — PCGamesN’s review specifically calls out the aesthetic as its main selling point over pure performance metrics.
That design doesn’t come at the cost of GPU room: 355mm of clearance comfortably fits a reference RTX 5090 Founders Edition (336mm) with margin to spare, and it’s the only case on this list that also supports DTX motherboards alongside mATX and Mini-ITX — a niche but genuine bonus for builders working with less common boards.
The D30 is also the most expensive case here at $109.99, and like the A3-mATX, it ships without any fans included, pushing the effective price closer to $140–150 once you’ve filled it out. GPU clearance also isn’t fixed: installing a larger ATX power supply drops the usable length to 305mm, which can create conflicts in builds already running a long card.
Best for: Builders who want a distinct aluminum-and-glass look and don’t mind paying a premium for it, especially if DTX motherboard support matters.
FAQ
What’s the biggest difference between an mATX case and a full ATX mid-tower?
Mostly footprint and motherboard slot count. mATX cases like these five are typically 15–20% smaller in external volume than ATX mid-towers such as those in our best mid-tower cases roundup, and mATX motherboards drop one or two PCIe/RAM slots most gaming builds don’t use anyway. GPU clearance and radiator support can match or even exceed ATX cases, as the Lian Li A3-mATX and DeepCool CH370 demonstrate here.
Which of these fits an RTX 5090 Founders Edition?
The reference RTX 5090 FE measures 336mm. The NZXT H3 Flow (352mm), Lian Li A3-mATX (415mm), Fractal Pop Mini Air RGB (365mm), and Jonsbo D30 (355mm) all clear it comfortably. The DeepCool CH370’s 320mm limit does not.
Do I need to buy extra fans for any of these cases?
The Lian Li A3-mATX and Jonsbo D30 ship with zero fans — budget $30–40 for two intake fans on either. The NZXT H3 Flow and DeepCool CH370 each include one rear fan and benefit from added front intake. Only the Fractal Design Pop Mini Air RGB arrives fully populated with three fans.
Can I fit a 360mm radiator in any of these cases?
Yes, in two of the five. The Lian Li A3-mATX supports 360mm across its top, bottom, or left panel, and the DeepCool CH370 supports 360mm in the front. The NZXT H3 Flow tops out at 280mm front, and both the Fractal Pop Mini Air RGB and Jonsbo D30 cap at 240mm.
Is mATX a good choice for a first build?
Yes — mATX keeps most of the simplicity of building in an ATX case (standard cable lengths, no ultra-tight tolerances) while trimming the footprint. If you want a smaller build than mATX allows, our small form factor PC build guide covers the additional planning Mini-ITX builds require.
The Bottom Line
The NZXT H3 Flow is the pick for most builders — 352mm of GPU clearance, back-connect cable routing, and a $56.99 price that undercuts everything else on this list. If footprint is the priority over price, the Lian Li A3-mATX fits flagship-class hardware into a 26.3-liter chassis that punches well above its size. And if a 360mm front radiator matters more than GPU length, the DeepCool CH370 delivers that at the lowest price of any case here.