NZXT has been showing off stunning new features and glamorous PC case designs for over two decades, yet its latest chassis effort might just send a few of its followers for a loop: The H2 Flow mid-tower is far smaller than its mini-tower predecessor, the H3 Flow. One need only glance at its shape to see why: Instead of chasing the familiar “fish tank” formula of wide dual-chamber towers and panoramic glass, NZXT instead compresses the traditional desktop front to back. The result is a compact, vertically oriented chassis that borrows ideas from small-form-factor builds without fully embracing the compromises they demand. 

The H2 Flow still supports beefy modern graphics cards, liquid cooling (if you choose carefully), and full desktop-class hardware, all while occupying remarkably little desk area. Gamers and creators who want powerful hardware without surrendering half their workspace to it will appreciate this space-saving design. In fairness, the $149 price and the need for a premium SFX power supply and a Mini-ITX motherboard may dissuade some builders, but inflation goes with the ITX territory. 

Design: The Power of Shallow Thinking

The second-smallest-footprint case we’ve tested in recent years, NZXT’s H2 Flow is close enough, dimensionally, to the open-frame Streacom DA6-XL that we won’t be bothered to quibble over the distance: A fraction of an inch deeper, the Flow’s 10.3-inch depth fits even the tiniest of (practical) desks. Perhaps that’s why NZXT chose to put its front-panel connectors on the actual front panel, rather than the top as we’ve so often seen on other 17-inch or taller mid-towers.

It almost looks like someone reduced the depth of a classic mid-tower by half, but only at first glance: Cases of old tended to have steel-framed plastic windows rather than tempered glass panels. And where a classic mid-tower case might have had FireWire and a pair of USB 2.0 back in the day, the H2 Flow goes with a nice, modern USB 3.2 Gen 2x2 for its Type-C connector and Gen 1 for its two USB Type-A ports. Audio jacks are also reduced from the classic headphone/mic pair; the single-connector headset jack adds an extra internal contact to work with a single-jack headset’s integrated microphone. NZXT finishes the design theme off with a classic lighted-ring power button.

(Credit: Thomas Soderstrom)

The H2 Flow’s back panel is holes and more holes, plus a divot for pulling off the snap-on top panel. The biggest holes are for your motherboard I/O panel and an SFX power supply, while the smaller holes are primarily for ventilation.  Grids of even smaller vent holes that fill the centers of the top and right-side panels match those previously seen on the front and lower left panel.

(Credit: Thomas Soderstrom)

The H2 Flow’s front and rear feet go across the case, with the gap in the rear foot you see above again visible on the left side of the picture below. Like so many other small-footprint cases, the H2 Flow tips its graphics card slot vertically, making room for large cards by making the case taller. The gap in the rear foot works as a passage for the graphics card’s DisplayPort or HDMI cable. The design’s biggest drawback is that it provides only 60mm (2 3/8 inches) of space under the back of the card in which to bend a DisplayPort or HDMI cable to clear the desk. (You may want to get an aftermarket HDMI or DisplayPort cable with an L-shaped connector.)

(Credit: Thomas Soderstrom)

The boxed section shown above can be seen inside the case below, where three replaceable expansion slot covers are clearly visible. A PCI Express x16 slot above these covers, on a daughterboard, connects the associated graphics card, via a riser cable, to your motherboard, which gets mounted on the other side of the internal sheet-metal divider. The 13 inches of provided card length should be more than adequate for most PC builders, though we’ve seen a few so-called “3.5-slot” graphics-card coolers that would be too thick for this space.

(Credit: Thomas Soderstrom)

At the top of the case, two factory-installed 120mm fans are mounted between the inner (structural) and outer (aesthetic) top panels in exhaust orientation, pulling heat away from both the graphics card and CPU cooler below.

(Credit: Thomas Soderstrom)

From a distance, you can see how all these features work together to keep the graphics card stable and cool while vertically mounted behind the motherboard.

(Credit: Thomas Soderstrom)

Turning the case around reveals that the partition through which the graphics riser cable traverses is actually the motherboard tray. That tray ends 35mm behind the back of the removable front fan mount, allowing the mount to hold 240mm- or 280mm-format radiators up to that thickness. The front fan tray is designed only to hold two (140mm or 120mm) fans, as the space behind is slightly insufficient to hold any available 360mm-format radiator.

(Credit: Thomas Soderstrom)

If you were fortunate enough to find a 4TB SSD in a $10 Amazon returns bin, you’ll be happy to see that the H2 Flow has two slip-in bays for 2.5-inch drives like these, located just under the SFX power-supply mount.

(Credit: Thomas Soderstrom)

Building With the NZXT H2 Flow

This case’s screw packs give you just enough to install a motherboard, a front radiator/fan set, your graphics card, and the power supply. The graphics card screws are already installed. You get a few #6-32 panhead screws to fill the motherboard standoffs, a few more #6-32 combo-heads to attach the power supply, and a few plastic-threading fan screws. There’s also an installation guide and a bundle of 10 zip ties.

(Credit: Thomas Soderstrom)

The front panel connects to our board using a 9-pin combined F_PANEL plug, HD Audio for the headset combo jack, a USB 3.x Gen 2x2 header cable for the Type-C port, and a 19-pin USB Gen 1 for the two USB Type-A ports. The top panel’s fans reach the motherboard header via a 4-pin PWM fan splitter cable.

(Credit: Thomas Soderstrom)

NZXT wanted to see its own SFX power supply in our build photos and sent an NZXT C850 SFX Gold to make that happen. Having already standardized on a different SFX model for our Mini-ITX case testing, I chose to test the case both ways.

(Credit: Thomas Soderstrom)

NZXT says that the H2 Flow has a 130mm maximum power supply length, but it’s clear to see that even a unit that’s as deep as the Mini-ITX motherboard (170mm) would easily fit. The 70mm relief at the top of the motherboard tray’s front edge is another great design choice, as it allowed one of our closed-loop CPU cooler’s hoses to more easily cross that barrier.

(Credit: Thomas Soderstrom)

Anyone who wants a seriously lit case could build with a cooler that has ARGB fans, but we think upsizing the cooler to the 280mm-format might be similarly visually impactful.

(Credit: Thomas Soderstrom)

Testing the NZXT H2 Flow

I mentioned the alternative configuration change above, regarding the SFX power supply, but here’s the standard configuration upon which I’ll base the performance analysis. Notice that only the power supply is different. (The standard SFX supply I usually use is the Cooler Master model mentioned below.)

I know what to credit for the performance differences: The H2 Flow’s design forced me to put the test radiator up front where it gets cooler air, improving CPU temperatures slightly. On the other hand, the cooler was no longer able to pull heat away from the motherboard’s voltage regulator, which slightly worsened its temperatures. Because the case had its own top fans, the increase in the voltage-regulator temperature appears slightly less significant than the decrease in CPU temperature.

As for the graphics card, the impact of cooling it with warm air from the CPU cooler appears minimal.

Coming out about par in cooling performance between the three readings, the H2 Flow impressed me a bit more with its clean win in noise control. That said, I should point out that most people tend not to notice sound-pressure-level differences of less than 3db.