PC builders and PC case makers toss around the hoary old term “SFF” (small form factor) as if it means something definitive. (It doesn’t.) But there’s no ambiguity around the newest small PC chassis from Lian Li we just tested, the $120 A4-H2O: It qualifies for the “S” in any builder’s book. At 11 liters of internal volume (a measure the SFF crowd also likes to toss around), the A4-H2O consumes just a 5.5-by-12.8-inch patch on your desk. The box has a similarly diminutive under-10-inch height. The biggest surprise, though: This Mini-ITX chassis lets you pack some very serious componentry in a seriously small space. If you pick your parts right, the A4-H2O can be the basis of a small powerhouse PC.
The Design: DAN Has the Plan
Lian Li designs most of its own cases, but this particular effort is based upon the A4-SFX design by DAN Cases, a boutique maker of small PC cases out of Germany. DAN has a following in PC enthusiast circles, and its popular designs have meant that the company has not been able to meet demand for its products, even at elevated prices. (Expect to pay more than $200 for the A4-SFX.)
Thus the collaboration with Lian Li. The A4-H2O combines the basics of the DAN design with the volume and economy of scale that Lian Li is known for. More important for PC builders, it means you should be able to buy one in a more reasonable timeframe, and for a more moderate price.
This chassis is decidedly for users who will be installing a dedicated video card (rare bird themselves, these days). It provides the added space to mount larger graphics cards, up to three-slot width, in an unusual configuration behind the motherboard. The expanded room doesn’t stop there, either, as the A4-H2O supports a CPU liquid cooling system, whereas the original DAN A4-SFX was designed for use with a low-profile fan-cooled heatsink.
The “front panel” ports are located at the leading edge of the A4-H2O’s left side, and include both a Type-A and Type-C port connected to proper Gen 1 and Gen 2 header cables. You also get headphone and microphone jacks, but just one button: a single power button near the top of this section. A reset button is notably absent.
As you’d expect, the A4-H2O relies on a compact SFX power supply (not included), not a full-size ATX supply. The power supply mounts in the front portion of the chassis. A power socket on the rear panel connects to that internally mounted SFX power supply via an internal passthrough cable. The power supply itself does not expose its rear panel on the back of the case, unlike most conventional chassis. You’ll spot four screws on the back, but these act as secondary security for the side panels, which actually fasten via snaps on all four corners.
To achieve the space savings, the A4-H2O separates your video card from its slot in the motherboard. Because the case is designed to hold a graphics card upside-down behind the motherboard, a PCI Express x16 riser cable runs from the bottom of its motherboard side to the top of its GPU side. You’ll plug this riser into the Mini-ITX board you install, and into the card once it is mounted.
With this riser cable is where the pricing for the case gets a little tricky. Lian Li offers options for PCI Express 3.0 and 4.0 riser cables, where the latter supports the former standard but costs more. The $35 difference between these cable options is hardly marginal on a case model that has a US base price of $120, so you’ll want to be sure you really need the 4.0 riser before you opt in for that.
Building in the Lian Li A4-H2O
With no case-mounted LEDs to indicate power-on status or hard drive activity, hooking up the chassis’ cables to your motherboard once the board is mounted inside isn’t very involved. The A4-H2O has headers only for the power button, HD Audio, and the USB 3 Gen 1 and 2 front ports to connect, in addition to the SFX power-supply passthrough cable mentioned earlier.
For this and future compact builds, Corsair offered us a pair of closed-loop liquid coolers, the H60i and H100i versions of its iCue RGB Pro XT series. Delivery of the larger (240mm) H100i ended up delayed, so we moved forward with the H60i. We replaced the stock blotch of thermal paste with Arctic MX-4, since we plan to use the cooler in future builds long after the original paste is gone.
As for the SFX power supply, PSU maker FSP seeded us with its 80 Plus Gold-rated, full modular Dagger Pro 850W. This tiny SFX model includes enough cable length to work even in some full-tower cases, and we’re tempted to use it that way in some future builds thanks to the inclusion of a PS/2 form-factor (aka full ATX) adapter plate. For this build, though, we’ll be using the Dagger Pro in its pure SFX guise.
Here’s a look at our full test configuration, which is anchored by a Core i5-9600K CPU, Asrock Mini-ITX motherboard, and a big GeForce RTX 2070 video card from Gigabyte…
We’re not going to beat around any bushes regarding build complexity: This one took hours. That wasn’t wholly the case’s fault; it was mostly due to our use of that 120mm cooler. The coolant line on the opposite side simply wasn’t flexible enough to snake around the rear of the power supply, and the 12-inch hoses weren’t long enough to mount the radiator farther forward in the chassis. As a result, we’d recommend using a 240mm (2x120mm) radiator with the lines exiting in front of the power supply, provided that its liquid lines are lengthier.
We had practically the opposite problem with the power-supply installation. Its extra long cables didn’t do us any favors, due to the minimal space for stuffing away excess cable run. This case would give you a great excuse to splash out and buy a short cable set from one of those custom cable companies like Pslate Customs, though PC builders who don’t need this much power output for the components they are installing can find a wider range of stock cable lengths in lesser-wattage SFX models.
All that said, there’s adequate space above the power supply and under the radiator to provide good ventilation. Seen here is the only position in which this particular closed-loop system’s radiator would fit, due to the hose length and stiffness, along with the plugged-in end of the power supply extension cable…
One nice touch: Since you won’t have access to the PSU’s back panel once the case is buttoned up and built out, the pop-off side panel makes it easy to switch the power supply on (if you forget to do so before finishing up the build).
Another positive aspect of the side panels is the perforations. Those with a soft spot for RGB components can still get a good view through the side panel vents.
Lian Li A4-H2O Performance
We’ve just fired up a new testing regimen for testing PC case thermals, so we don’t currently have another chassis on the bench this small to compare numbers with. (We will be expanding our testing pool in coming months.) So, for now, we tested the A4-H2O against itself in closed-panel and open-panel configurations to see how well it would contain noise and let out heat.
We set the CPU to a fixed voltage and frequency to maintain a relatively consistent load.
In case you’re wondering, that is an 8-degree CPU core and a 7-degree GPU temperature reduction achieved simply by opening the case. Meanwhile, our component noise measurement went up by around 1.5 decibels with the case open. The noise level increased from 36.4 to 37.9 decibels when measuring at a 45-degree angle from the left front corner, and from 39.2 to 40.8 decibels when measuring at the same angle from the right front corner.
Conclusion: A Slick Chassis With Tight Tolerances
The A4-H2O is a brilliant design capable of holding a high-end GPU and an overclocked Core i5 processor at acceptable temperatures. With our efforts partially undone by component selection, we advise that novice builders may want to wait to see how other A4-H2O builds have turned out, and choose their parts accordingly, especially in terms of AIO liquid coolers.
But get the right mix, and this chassis will vie with the Streacom DA2 V2 as one of our favorite Mini-ITX chassis for tricked-out builds. And it won’t cost you half of what the DA2 V2 will.
