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The 11 Best Smallest ATX Cases for Compact PC Builds

Written by Azzief Khaliq
Last updated Aug 4, 2021

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smallest atx cases

If you wish to build a compact computer without sacrificing the features of a full-sized motherboard, our list of the best smallest ATX cases will come in handy. From thin HTPC-friendly cases to squarish tempered glass beauties, each case on this list strikes a balance between functionality, space efficiency, and aesthetics.

Our Picks for Best Small ATX Case

These cases were selected first and foremost to offer committed ATX motherboard users some space-saving options for their PC build. But if you’re not 100% decided on using an ATX motherboard, why not consider Micro ATX instead?

A Micro ATX PC case would be smaller than almost all of the products here, and you’d really only sacrifice one PCIe x16 slot and maybe two or three SATA ports at most. For more info on the differences between ATX, Micro ATX, and Mini ITX, check out our guide on motherboard sizes. If you’re already committed to going ATX, let’s get into our picks.

1. Raijintek Thetis Window

Measurements (H x W x L)14.2 x 8.3 x 14.4 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length12.6 inches
Maximum CPU Cooler Height6.7 inches
Expansion SlotsSeven
Fan Mounts• 2x 120 mm (top)
• 1x 120 mm (rear)
• 1x 120 mm (bottom)
Radiator Support240 mm radiator (top)
Drive Mounts• 2x 3.5” drives
• 2x 2.5” drives
I/O Ports• 2x USB 3.0
• Audio In/Out

Raijintek isn’t a name you often hear of, but the company’s Thetis case stands out as one of the smallest ATX cases available. We like the Thetis because it supports standard-sized components despite its relatively compact dimensions. You won’t have to worry about getting an SFX PSU or a miniature GPU with the Thetis.

One potential drawback is that the Thetis seems to only support an inverted motherboard layout. An inverted layout means the motherboard is mounted upside-down, with the GPU closer to the top panel. There’s nothing wrong with that, but it is something to be aware of in case you don’t like how it looks.

The Raijintek Thetis also only comes with one case fan from the factory. We highly recommend you add at least one intake fan to help with airflow.

raijintek thetis build

Source: acquacow on Flickr

Depending on your preferences, this case’s design will either be perfectly minimal or painfully dull. We don’t mind it all, although we wouldn’t particularly call it good-looking. Its brushed aluminum panels do give the Thetis a premium feel, at least.

The Rajintek Thetis is available in black and silver. Raijintek also sells a non-windowed version called the Thetis Classic if you’re not keen on the tempered glass side panel.

2. NZXT H510i

Measurements (H x W x L)18.1 x 8.3 x 16.8 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length15 inches
Maximum CPU Cooler Height6.5 inches
Expansion Slots• Seven horizontal
• Two vertical
Fan Mounts• 2x 120 / 140 mm (front)
• 1x 120 / 140 mm (top)
• 1x 120 mm (rear)
Radiator Support• 280 mm (front)
• 120 mm (rear)
Drive Mounts• 3x 3.5” drives
• 2x 2.5” drives
I/O Ports• 1x USB 3.2 Gen 1 Type-C
• 1x USB 3.2 Gen 2 Type-A
• Audio In/Out

NZXT’s H510i case is one of the most popular ATX cases and it’s not hard to see why. The combination of sleek looks, reasonable pricing, and relatively compact dimensions makes it one of the most appealing compact ATX cases available.

The H510i comes with two pre-installed RGB LED strips and Aer 2 case fans, with a Smart Device 2 to control both. It also has a 280 mm radiator bracket pre-installed, although you can easily remove it if you prefer an air-cooled CPU.

The NZXT H510i only has two front USB ports, but we like its combination of a USB-C port and a 10 Gbps USB 3.2 Gen 2 port. What the H510i lacks in I/O quantity it makes up for in quality. Note that the USB-C port will require a USB-C header on your motherboard, so check that your motherboard has one before getting too excited about it.

The H510i comes in white, black, and a black and red combo. If you’re on a more limited budget, NZXT also sells a non-RGB version called the H510 which would save you around $30.

3. Lian-Li O11 Dynamic Mini

Measurements (H x W x L)15 x 10.6 x 16.5 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportSFX
Maximum GPU Length15.5 inches
Maximum CPU Cooler Height6.8 inches
Expansion SlotsThree / five / seven (depending on back panel)
Fan Mounts• 3x 120 mm / 2x 140 mm (top)
• 2x 120 / 140 mm (side)
• 3x 120 mm / 2x 140 mm (bottom)
• 1x 120 mm (rear)
Radiator Support• 240 / 280 / 360 mm (top)
• 240 / 280 mm (side)
• 240 / 280 / 360 mm (bottom)
Drive Mounts• 2x 3.5” / 2.5” drives
• 2x 2.5” drives
I/O Ports• 1x USB 3.1 Type-C
• 2x USB 3.0
• Audio In/Out

Lian-Li’s O11 Dynamic Mini is a scaled-down version of its beloved O11 Dynamic case. The O11 Dynamic Mini retains the look of its bigger brother but has a shorter and wider form factor. It’s still not tiny, but we actually like the O11 Mini’s proportions more than the original’s.

Standout features on the Lian-Li O11 Dynamic Mini include a dual-chamber design, mounting locations for up to nine 120 mm fans, and a modular water cooling pump stand. The O11 Dynamic Mini also has a modular backplate that lets you choose between having three, five, or seven expansion slots.

lian li o11 mini build

Source: u/Exotli8

The Lian-Li O11 Dynamic Mini can also be equipped with an optional vertical GPU bracket if you want to show off your card. And showing off is the name of the game with the O11 Dynamic Mini. With its clean lines and full tempered glass front and side, it’s our pick for the best-looking case here.

Do note that you’ll need an SFX or SFX-L power supply if you plan to build in the Lian-Li O11 Dynamic Mini. While not ideal, we think it’s worth it for a case of this quality. The O11 Dynamic Mini comes in black, white (which is more of a black-and-white combination), and a striking all-white colorway called “snow white.”

4. Thermaltake Core G3

Measurements (H x W x L)17.9 x 5.5 x 14.6 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportSFX
Maximum GPU Length12.2 inches
Maximum CPU Cooler Height4.3 inches
Expansion SlotsTwo
Fan Mounts• 2x 120 mm (front)
• 1x 120 mm (top)
Radiator Support240 mm (front)
Drive Mounts2x 3.5”/2.5” drives
I/O Ports• 2x USB 3.0
• 2x USB 2.0
• Audio In/Out

The Thermaltake Core G3 is a compact ATX case with one huge selling point: its 5.5-inch width. You’d be hard-pressed to find a mainstream ATX case that’s even remotely as thin as the Core G3.

Sacrifices have been made in pursuit of thinness, though. For one, the Core G3 only has enough room for a compact SFX PSU instead of the standard ATX-sized PSU you’re likely familiar with. That’s not a problem if you’re buying an all-new rig, especially since SFX PSUs are more common now. But it may be an unwelcome extra expense if you’re transplanting an older rig into the Core G3.

core g3 build

Source: carleeno on PCPartPicker

Another potential issue is how Thermaltake designed the GPU mount in the G3. To achieve that 5.5-inch width, graphics cards in the Core G3 mount vertically right up against the side panel. This leads to higher GPU temperatures, especially for air-cooled cards. And the Core G3 also lacks any convenient cable management features which might further impede the cooling in your rig.

core g3 temps

86 degrees Celsius on the GPU isn’t ideal. Source: Kitguru

Like Thermaltake’s Core P-series of cases, the Thermaltake Core G3 can sit either horizontally or vertically. This makes it an ideal ATX case for a living-room PC that needs to fit in a shelf or A/V cabinet. Thermaltake doesn’t offer any color or side panel options for the Core G3.

5. Corsair iCUE 220T RGB Airflow

Measurements (H x W x L)17.7 x 8.3 x 15.5 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length11.8 inches
Maximum CPU Cooler Height6.3 inches
Expansion SlotsSeven
Fan Mounts• 3x 120 mm / 2x 140 mm (front)
• 2x 120 / 140 mm (top)
• 1x 120 mm (rear)
Radiator Support• 280 / 360 mm (front)
• 240 mm (top)
• 120 mm (rear)
Drive Mounts• 2x 3.5” drives
• 2x 2.5” drives
I/O Ports• 2x USB 3.0
• Audio In/Out

The Corsair iCUE 220T RGB Airflow is one of the most visually striking compact ATX cases on our list. Its angular front panel perforations aren’t just for show, though; the panel’s design is meant to aid airflow, especially when combined with the three included Corsair SP120 intake fans.

The iCUE 220T RGB also has a Corsair Lighting Node Core to control the RGB lighting on the fans. Unfortunately, since it’s a Node Core, you can’t add any addressable RGB LED strips to the case. If you want addressable RGB strips, you’ll have to pony up extra money for a Node Pro and install it yourself.

It’s not a deal-breaker, but it is slightly disappointing. After all, the NXZT H510i includes addressable RGB strips and fans for a lower price than the iCUE 220T RGB Airflow.

icue 220t build

Source: u/knobody614

There’s a lot to like about the iCUE 220T RGB Airflow, but we’d recommend swapping the stock fans if you want to take advantage of the airflow-centric design. Check out our list of the best RGB fans for some higher performance options.

The Corsair iCUE 220T RGB Airflow is available in black or white. We think the white finish is particularly striking.

6. Phanteks P300A Mesh

Measurements (H x W x L)17.7 x 7.8 x 15.7 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length14.0 inches
Maximum CPU Cooler Height6.5 inches
Expansion SlotsSeven
Fan Mounts• 2x 120 mm / 2x 140 mm (front)
• 1x 120 / 140 mm (top)
• 1x 120 mm (rear)
Radiator Support• Up to 240 / 280 mm (front)
• 120 mm (rear)
Drive Mounts• 2x 3.5” / 2.5” drives
• 2x 2.5” drives
I/O Ports• 2x USB 3.0
• Audio In/Out

Phanteks is known for its high-airflow P-series cases like the P400A and P500A. The P300A Mesh keeps the airflow-focused design of the larger models in a much more compact size that’s perfect for a smaller ATX rig.

Like Phanteks’ other airflow cases, the Phanteks P300A Mesh sports a single-layer metal mesh front panel. The company claims that the “Ultra-Fine Performance” mesh is fine enough to keep dust from entering your system without needing an extra layer of filtering.

phanteks p300a build

Source: Evan_Games on PCPartPicker

The Phanteks P300A Mesh doesn’t have any standout features beyond the airflow-focused design and modest dimensions. It’s a budget case, reflected in the no-frills design and single included exhaust fan.

You should definitely add fans if you get the Phanteks P300A; reviews show a significant improvement in GPU temperatures by adding two intake fans. There’s no need to go overboard though. An affordable set of fans like the Arctic F12 PWM two-pack would be perfect. They’re a great option for any other cases on our list that only come with one stock fan, too.

7. Fractal Design Define 7 Compact

Measurements (H x W x L)18.8 x 9.4 x 21.5 inches
Motherboard SupportE-ATX, ATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length12.4 inches (with HDD cage), 19.3 inches (without cage)
Maximum CPU Cooler Height7.3 inches
Expansion Slots• Seven horizontal
• Two vertical
Fan Mounts• 3x 120/140 mm (front)
• 1x 120/140 mm (rear)
• 3x 120/140 mm (with ventilated top panel)
• 2x 120/140 mm (bottom)
Radiator Support• Up to 280/360 mm (front)
• Up to 360/420 mm (top)
• Up to 240/280 mm (bottom)
Drive Mounts• 4x 2.5” drives (2 by default)
• 14x 2.5”/3.5” drives (6 by default)
• 1x 5.25” optical drive
I/O Ports• 1x USB-C 3.1 Gen 2
• 2x USB 3.0
• 2x USB 2.0
• Audio In/Out

Fractal Design’s Define 7 Compact takes all the core features of its Define 7 (one of the best silent PC cases on the market) and crams it all into a small package without sacrificing ATX compatibility. It’s still one of the larger cases on our list, but it’s tiny compared to the full-size Define 7.

As expected, the Define 7 Compact has a few notable features that identify it as a modern Fractal Design product. These include a fully detachable top for easy assembly, “industrial high-density sound damping” to cut down on noise, and the choice between a solid steel or ventilated top panel.

fractal design define 7 compact build

Source: Reddit

You might want to consider the ventilated panel, too, as CPU and GPU temperatures can get relatively high in the Fractal Design Define 7 Compact. The smaller dimensions lead to even higher temperatures than the full-size Define 7, so you definitely should pick your parts and cooling solutions wisely.

fractal define 7 compact temps

Source: TechPowerUp

The Fractal Design Define 7 Compact is also one of the best-equipped cases on our list for front panel connectivity. With one USB-C port, two USB 3.0 ports, and two USB 2.0 ports, you might not even need the ports on your rear I/O for peripherals.

The Fractal Design Define 7 Compact is available in white and black. You also have the choice of a solid side panel or a tempered glass side panel in either dark or light tints.

8. Fractal Design Meshify 2 Compact

Measurements (H x W x L)18.7 x 8.3 x 16.7 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length13.4 inches (with front fan) / 14.2 inches (without front fan)
Maximum CPU Cooler Height6.6 inches
Expansion SlotsSeven
Fan Mounts• 3x 120 mm / 2x 140 mm (front)
• 2x 120 / 140 mm (top)
• 1x 120 mm (rear)
• 1x 120 mm (bottom)
Radiator Support• Up to 240 / 360 mm (front)
• Up to 240 mm (top)
• 120 mm (rear)
• 120 mm (bottom)
Drive Mounts• 2x 3.5” / 2.5” drives
• 4x 2.5” drives (two trays included)
I/O Ports• 1x USB 3.1 Gen 2 Type-C
• 2x USB 3.0
• Audio In/Out

What if you like the Fractal Design Define 7 Compact but can’t live with those temperatures? That’s where the Meshify 2 Compact comes in.

The Meshify 2 Compact takes the core of the Define 7 Compact but swaps the steel front door with a much less restrictive mesh panel. The front panel is two-layered, combining that striking angular mesh panel with an extra nylon layer for even more dust filtration. If your environment allows, you can remove the nylon filter to improve airflow even further.

meshify 2 compact build example

Source: u/JMXCVIII

The mesh front leads to a significant improvement in temperatures, according to TechPowerUp’s testing. CPU and M.2 drive temperatures, especially, are much better:

fractal meshify 2 compact temps

Source: TechPowerUp

Beyond the new front panel, the Fractal Design Meshify 2 Compact is much like the Define 7 Compact. You lose the two USB 2.0 ports, but they’re identical in features and component support beyond that.

The Fractal Design Meshify 2 Compact comes in black and white, with the option of a solid side panel or a tempered glass panel with three levels of tint (dark, light, and clear).

9. Cooler Master MasterBox Q500L

Measurements (H x W x L)15 x 9.0 x 15.2 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX
Maximum GPU Length14.2 inches
Maximum CPU Cooler Height6.3 inches
Expansion SlotsSeven
Fan Mounts• 2x 120 / 140 mm (front)
• 1x 120 mm (rear)
• 2x 120 mm (bottom)
Radiator Support• 120 / 240 mm (top)
• 120 mm (rear)
Drive Mounts• 2x 3.5” / 4x 2.5” drives
I/O Ports• 2x USB 3.0
• Audio In/Out

Cooler Master’s Q500L is the larger version of the Q300L Micro ATX case that retains its smaller sibling’s features and design language. This means that the Q500L has the same perforated chassis (for easy fan installation) and patterned magnetic dust filters as the Q300L.

The Cooler Master Q500L is also as versatile as the Q300L, including the ability to be used vertically or horizontally. The Q500L also supports inverted motherboards, which goes hand-in-hand with the movable side-mounted I/O panel. The panel can be moved to one of three locations depending on which suits your case or motherboard orientation the best.

cooler master q500l build

Source: Rukkerz on PCPartPicker

Your PSU mounts towards the top front side of the Cooler Master Q500L with an ATX motherboard. It’s held in place by a PSU bracket that can be moved up or down slightly to make room for a long GPU or a top-mounted radiator. If you’re using a Micro ATX or Mini ITX board, the PSU can go in the usual place in the bottom rear of the case.

q500l psu bracket

The Cooler Master Q500L’s PSU bracket. Source: Cooler Master

The Cooler Master Q500L only ships with a single 120 mm exhaust fan, making for higher than ideal temperatures. Tom’s Hardware found that moving the default exhaust fan to an intake position “resulted in a 5-percent drop in CPU temps and GPU temps 8 percent lower than stock configuration.”

The Cooler Master Q500L is an interesting small ATX case that’s worth checking out if you like versatility and options. Just be aware of the cooling limitations and plan accordingly. The Q500L only comes in one color and doesn’t come in a non-windowed variant.

10. Sliger Cerberus X

Measurements (H x W x L)15 x 6.8 x 14.1 inches
Motherboard SupportATX, Micro ATX, Mini ITX
PSU SupportATX, SFX, SFX-L
Maximum GPU Length13 inches
Maximum CPU Cooler Height1.9 inches (ATX PSU), 3 inches (“SFX plate” PSU mounting), 5.8 inches (internal SFX PSU)
Expansion SlotsEight
Fan Mounts• 1x 120 mm (front)
• 2x 140 mm (bottom)
Radiator Support• 240 mm (front)
• 240 mm (bottom)
Drive Mounts• 2x 3.5” / 2.5” drives
I/O Ports• 2x USB 3.0
• Audio In/Out

Sliger’s Cerberus X is probably the smallest ATX case you can buy right now. It’s slightly taller than the Raijintek Thetis, but is narrower and shorter, making for a compact ATX case that’s just a hair above the 20-liter small form factor cutoff.

Despite being so small, the Cerberus X still manages to support Extended ATX motherboards. Admittedly, it will only accommodate ones with maximum dimensions of 12 x 13.2 inches, like the MSI MEG Z490 Godlike. Still impressive, though.

The Cerberus X also supports ATX and SFX PSUs, with the latter featuring two mounting options. You can either have the PSU mounted in a more traditional position on the rear panel of the case or internally towards the front. The latter gives you more space for a CPU cooler which is handy if you prefer air cooling your CPU.

sliger cerberus x psu positions

From L to R: internal mount SFX, rear-mounted SFX, rear-mounted ATX. Source: Sliger

An ATX PSU would limit you to an AIO CPU cooler, but Sliger gives you the option of purchasing one with the case. You can also choose between a vented or windowed side panel and add a handle if you want a portable PC.

cerberus x build

Source: Sliger

The Sliger Cerberus X isn’t a cheap case by any means, and that’s its biggest downside. But its small size and ability to accommodate high-end hardware makes it a unique proposition amongst compact ATX cases.

The Sliger Cerberus X comes in black, gray, and white. You also can mix and match panel colors or even spec a custom paint job if you so desire.

11. SilverStone GD09B

Measurements (H x W x D)6.7 x 17.3 x 14 inches
Motherboard SupportSSI CEB, ATX, Micro ATX
PSU SupportATX
Maximum GPU Length12.2 inches
Maximum CPU Cooler Height5.4 inches
Expansion SlotsEight
Fans• 2x 120 mm (right panel)
• 1x 120 mm or 80 mm (left panel)
• 2x 80 mm (rear)
Storage• 1x 2.5" SSD
• 2x 3.5" HDD (one with 2.5" support")
• 1x 5.25" optical drive
I/O Ports• 2x USB 3.0
• Audio In/out

We’ve featured the SilverStone GD09B previously in our list of the best horizontal PC cases, but its relatively small size and 27-liter volume justify inclusion here too. The GD09B is larger than its closest rival on our list, the Thermaltake Core G3. However, the added size does give it a few advantages.

For one, you won’t need an SFX power supply to build a PC in the GD09B. It takes standard ATX PSUs fine and will also fit a taller CPU cooler. Maximum GPU length is the same as the G3, but the GD09B doesn’t place it directly against the side panel. That should help keep temperatures down.

silverstone gd09 build

Source: SmoggyTwinkles on Imgur

The SilverStone GD09B also has room for an optical drive. It’s a bit of an odd inclusion these days, but that makes it perfect for a living room PC that may need to play Blu-Ray or audio CDs from time to time. It’ll also accommodate the same sorts of motherboards as the Cerberus Sliger X, making it a viable option if you plan to use a high-end E-ATX board.

SilverStone also sells a version with a single USB-C port on the front. If you want that one, make sure to look out for the model number GD09B-C. It’s easy to mistake the two otherwise.

Conclusion

The days of ATX rigs needing bulky mid or full-tower cases are behind us. These smallest ATX cases on our list show that you can enjoy all the features of an ATX motherboard while also cutting down on the amount of room your build takes up.

We don’t think there’s an outright winner here, as each case will appeal to different users for different reasons. It’ll come down to a matter of aesthetic preference and what you’re willing to sacrifice for a compact computer case. If you need extra guidance on that front, be sure to check out our guide to choosing a PC case.

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