Mini ITX cases under 4 liters: the short list

Search for a Mini ITX case under 4 liters and most of what comes back is 5 and 7 liter cases. I designed my own at 3.73 liters because I could not find one I wanted to buy. So this week I went back and checked the candidates against each maker’s own spec page.

Short version for the skimmers. Of the cases that usually come up, two commercial ones make it under 4 liters on their maker’s page. They are the Velkase Velka 3 at 3.99 L and the NFC Skyreach 4 Tiny at 3.38 L. Only the Velka 3 takes a graphics card with a Mini ITX board. So if you want a graphics card in under 4 liters, the choice is the Velka 3 at $159.99 or a printed case like my Under4L. The Velka 3 fits four times as many cards. It does not fit more of the ones you can buy new.

Which Mini ITX cases are actually under 4 liters?

I started with the names that come up whenever this question gets asked, then read each maker’s page instead of the roundup posts. Roundups round numbers and copy each other. The maker is the only one with something to lose if the figure is wrong.

Two made it. The Velka 3 rev 3.0 is 3.99 L by Velkase’s own figure. The Skyreach 4 Tiny is 3.38 L by NFC’s. Here they are next to mine, plus one near miss, in the same table format I use on every case post.

A few notes so the table does not mislead. Volume is each maker’s headline number, and Velkase is the only maker here that publishes both an outside figure and an inside one (3.81 L). The Velka 3 publishes two card envelopes, so it gets two rows. Its 140 mm height is for the card itself, and Velkase says 148 mm once the power cables are in. The Under4L price is for the STL files. You print it yourself, so add filament and about 12 hours on a Bambu P1S.

Why most tiny case lists stop at 5 liters

The SGPC K39 is the case I expected to be on this list. The model number reads like 3.9 liters. SGPC’s own product page calls it a “5.1L Ultra-Small SFF Case”. That is a perfectly good small case. It is not a sub-4 liter one.

The K39 page also shows the naming problem I keep running into. SGPC says the case takes a GPU “up to 185mm in length and 40mm in height”, or 50 mm after you raise the side panel on the included standoffs. Raising a side panel can only add room across the slots. So that “height” is what I would call thickness, and SGPC never publishes how tall a card can be.

The InWin Chopin is the other name that comes up. The UK retailer mini-itx.com lists it at 4.45 litres, with an internal 150W power supply and room for a 43 mm cooler. InWin’s own page would not load for me, so treat that as a retailer figure. Either way it is over 4 liters, and the listing mentions no graphics card slot.

Four liters is a hard line for a reason. Below it, something has to give: the graphics card, the power supply, or the cooler. Every case in the table gave up at least one.

Velka 3 vs Under4L: which graphics cards fit

I ran both envelopes against my GPU dimensions dataset, which has length, height and thickness in millimetres for 300 cards. For the Velka 3 I counted a card if it fit either of Velkase’s two envelopes. For the Under4L I used 182 x 69 x 40 mm.

The Velka 3 fits 47 of the 300. The Under4L fits 11. The reason is almost all height. I went through that in the SFF case GPU clearance guide. A 69 mm limit means low profile cards only, and there are very few of those.

Four times as many cards sounds decisive. Then I filtered to the cards the dataset flags as sold new at US retail, since most of the 47 are used market cards or imports.

Seven each. Only two cards fit both: the ASRock RX 6400 Low Profile and the ASRock Arc A380 Low Profile. The rest of each list is a card the other case cannot take. That availability flag is a snapshot, so check the card is still in stock before you plan around it.

Where the Velka 3 spends its extra quarter liter

It spends it on height. A 140 mm limit opens up standard height cards like the Zotac Solo and the PNY single fan models, which is where most of the 47 come from.

But its length limit stops at 175 mm, or 179 mm for a card no thicker than 41 mm. The Gigabyte low profile cards are 181 and 182 mm. So the low profile RTX 5060 and RTX 5050 that fit the Under4L are locked out of the Velka 3 by a few millimetres.

The result is a tie I did not expect. Under 4 liters, the fastest card in my dataset that you can buy new in the US is an RTX 5060 at 145 W, and it fits both cases. The difference is which RTX 5060. The Velka 3 takes the short standard height ones. The Under4L takes the Gigabyte low profile one.

The rest of the build is closer than the volume gap suggests. Both cases cap the CPU cooler at 37 mm. Both need Flex ATX, and neither fits SFX. The Velka 3 caps the supply at 165 mm long, while the Under4L takes a standard 170 x 82 x 41.2 mm unit. The Velka 3 allows 42 mm tall memory against 37 mm in mine. Both need a riser cable. The full Under4L limits, and how it got from 4.7 L to 3.73 L, are in the 3D printed Mini ITX case writeup.

Why the Skyreach 4 Tiny is smaller and takes no card

The Skyreach 4 Tiny is the smallest case here at 3.38 L, and it does support Mini ITX boards. What it does not do is take a graphics card with one. NFC lists low profile GPU support only “With STX motherboard and custom I/O (Rear Bezel)”.

It is built around an internal HDPLEX supply, and NFC recommends a 250 W GaN unit. It also has the most cooler room of anything in the table, about 47 mm. That makes it a good home for a build that runs on integrated graphics. I run my own media server that way, and the setup is in my post on passing an iGPU through to a Plex container. It is a Mini ITX case under 4 liters, just not one for a discrete card.

How to read a case volume figure without getting burned

Three habits would have saved me time here. First, get the number from the maker. The K39’s model number reads like 3.9 liters and SGPC says 5.1. Second, ask whether the figure is outside or inside. Velkase gives both, and the gap is 0.18 L, which is most of the difference between the Velka 3 and the Under4L. Third, check what each word means. SGPC’s “height” is thickness.

Card lengths need the same care. Vendors often publish the bare card, and the bracket adds 10 to 13 mm. I wrote about that, and about slot labels, in the SFF GPU dimensions database post. If you are within 10 mm of a limit, measure the card you own.

Which one I would buy

I designed one of these, so weigh my opinion with that in mind.

If you do not own a printer, buy the Velka 3. It arrives finished, and $159.99 is a fair price for a case you do not have to print. If you have a printer with a 256 x 256 mm bed and an enclosure for ABS, the Under4L costs $9.98 in files plus filament, and it takes the low profile RTX 5060. If your build has no graphics card, the Skyreach 4 Tiny is smaller than both. And if you can live with 5.1 liters, the K39 on sale is the cheapest route of all, and the card list opens right up.

What I would not do is buy any of them off a roundup figure. Every case figure in this post came off a maker or retailer page this week, and one of those cases turned out more than a liter bigger than its name suggests.

FAQ

What is the smallest Mini ITX case that takes a graphics card?

Of the cases I checked against their maker’s own page, the smallest commercial one is the Velkase Velka 3 at 3.99 L. My printed Under4L is 3.73 L. The NFC Skyreach 4 Tiny is smaller at 3.38 L, but NFC only lists graphics card support with an STX board, not Mini ITX.

Is the SGPC K39 under 4 liters?

Not according to SGPC. Its own product page calls it a 5.1L case. The model number reads like 3.9 liters, which is probably where the smaller figure comes from.

Can a full height graphics card fit in a 4 liter case?

Yes, if it is short. The Velka 3 takes cards up to 140 mm tall and 175 mm long at 43 mm thick. Against my 300-card dataset that is 47 cards, and most of them are compact single fan models.

What power supply do sub-4 liter cases use?

Flex ATX, in the two that take a graphics card. The Velka 3 caps the supply at 165 mm long, and the Under4L takes a standard 170 x 82 x 41.2 mm unit. Neither one fits SFX. The Skyreach 4 Tiny is built around an internal HDPLEX supply instead.

What is the fastest graphics card that fits a case under 4 liters?

Among the cards my dataset flags as sold new in the US, an RTX 5060 at 145 W fits both the Velka 3 and the Under4L. They just take different models: short standard height cards from PNY and Zotac in the Velka 3, and the Gigabyte low profile card in the Under4L.

Get the files

The Under4L is two STL files, the skeleton and the shell, with an assembly guide and the screw and riser specs. The Under4L case files are on Gumroad for $9.98.