HP Omen 45L ATX PC Case

Have you ever seen a factory-built PC and wondered why, oh why, you couldn't build your own system using that same case? This question has plagued PC buyers ever since the build-your-own-PC market emerged. From recent Dell and Alienware gaming systems to old Compaq business towers and even early IBMs desktops, we’ve seen a string of heavy-duty PC cases with attractive design features that we would have wanted, had they only been built around accepted fitment standards…and, well, made available. The 28-pound HP Omen 45L ATX Case ($349.99) would have been one of those bemoaned wish-list cases (we tested the HP Omen 45L as a prebuilt PC a while back), except for two things: It's completely standard, and HP made it available as a separate purchase. And it proves a solid, good-looking chassis for DIY builders. That said, with its tall profile and so-called Cryo Chamber (an isolated section up top designed for a radiator), liquid-cooling hounds are the main perpetrators who will want to pay this big tower the closest attention.

With the Omen 45L's nowadays-common glass front and left side panel, and its standard number of expansion slots (seven), ventilation slots mark the biggest difference between the Omen 45L and other heavy steel chassis. (Oh, and that big Omen diamond logo on the front.)

The ventilation slots go all the way across and mark the air inlets for the front panel and the Cryo Chamber top. In the Cryo Chamber, you have a separate compartment for which intake and exhaust path are isolated from the main structure's airflow. It's HP's method of preventing warm air from exiting the radiator into the case or from entering the radiator from the case. All four panels that make up the chamber gap are bent at the center to create a rectangular funnel shape that tapers toward the center from each side.

Pictures of the Cryo Chamber's intake slot repeatedly reveal a button above each side panel, which, if your curiosity was getting the best of you, are side-panel latches. Pressing the release buttons above the glass left side panel allows it to tilt away at the top and be lifted off a lip at the bottom of the opening, for safe removal.

The front panel also has button latches, but you’ll need two hands to release it. Tilting it forward allows two claw hooks near its bottom edge to be lifted out of holes in the structural panel behind it.

As if to prove our point about the Omen 45L having a scant few features to set it apart from other heavy steel cases, the front-panel port section (at the front of the top panel) lacks even one USB Type-C connector. HP instead adds a pair of legacy USB 2.0 ports at roughly a tenth the peak data rate of the case's two USB 3.x Type-A ports. Conversely, its combination of headset combo and microphone jacks is an unexpected bonus that allows users to natively connect their headsets regardless of whether they use a combo plug or separate headphone and mic plugs.

The top panel features a removable cover that hides a two-140mm-fan (or three-120mm-fan) radiator mount that's actually only 396mm long. While most 360mm-class radiators advertise an actual length of 394mm to 396mm, several current models fall into the 400mm-to-406mm range. So mind those radiator specs if you're looking to install a long one up here: It might get evicted from the Cryo Chamber for its size! In the other dimension, HP's designers were thoughtful enough to leave space for radiator and fan combos up to 60mm thick.

The bottom panel features three vents and two rubber-faced plastic feet. Only two of the vents have dust filters, and only the one under the power supply is accessible from the outside. Attached via strip magnets along its edges, the power supply filter isn't accessible from an edge but instead requires owners to turn their case on its side for maintenance.

A relatively plain interior features two large grommet-filled cable passages and an enormous hole that allows CPU cooler plate access, the latter extended to almost the width of a full ATX motherboard for unknown reasons. While the case has more than enough interior space for an Extended ATX (EATX) board, a raised portion that protrudes inward far enough to make contact with any oversize boards is positioned with only around 0.2 inch of clearance in front of a standard 9.6-inch-deep ATX motherboard.

The steel panel on the right hides two 2.5-inch drive trays that are mounted to the back of the motherboard tray, an ARGB/RGB controller in the formerly discussed raised area that's recessed on this side, a 10.6-inch-deep power supply bay, and a 3.5-inch drive cage that prevents the power supply bay from being any deeper.

The lighting controller features both ARGB and RGB outputs and is controlled via a USB 2.0 interface. Powered by a SATA power cable, its SATA-style data connector is completely undocumented and apparently pointless given its factory-attached USB 2.0 internal header cable.

The two 3.5-inch drive trays have vibration-damping mounting pins at the sides, plus a set of holes on the bottom that allows the installation of 2.5-inch drives as an alternative. While HP documentation suggests that a right-angle cable may be needed, we found that the 1.25 inches or more of space between the end of our 3.5-inch drive and the side panel was more than sufficient to bend a straight cable without overstressing its connector.

A vent below the drive cage features a permanently affixed dust filter.

With its power supply dust filter hard to reach and its drive-cage dust filter impossible to remove, the Omen 45L's front-panel filter is the highlight of its dust-thwarting strategy. Simply lifting the two buttons of the face-panel latch and tilting it forward allows access, and the filter itself is latched via a single tab at the top. Note that mounting holes of the lowest fan are threaded for machine screws since some of these holes are inaccessible from the rear, and that only the top two fans are cable of holding a radiator on the opposite side.

The Omen 45L ATX PC Case (its full product name) includes a giant envelope in which we found nothing but the warranty sheet, a separate booklet that contains little more than a link to the HP website, a CD that contains little more than the paper documentation, four screws for the front panel's lower fan mount, 11 screws to match the nine standoffs of ATX, and an extra standoff that could be used to fill the optional mounting point found along the rear edge of some ATX motherboards. The package does not include screws to install 2.5-inch drives, even though the case includes two dedicated 2.5-inch drive trays plus two 3.5-inch trays with 2.5-inch mounting points.

HP wants you to surf its site for the manual, which proved far easier to find than we expected. Then again, HP could have avoided that annoyance by providing this direct link.

The Omen 45L includes a pair of cables for the ARGB/RGB controller, a power-switch cable for your front-panel header, an HD Audio cable for front-panel headset combo and microphone jacks, a Gen 1 cable for the two USB 3 Type-A connectors, and a USB 2.0 cable for the legacy Type-A connectors. One of the RGB controller's two cables also fits an internal USB 2.0 header and is used for data input, while the other connects to a front-panel LED header.

Those willing to zoom in on the last connector we mentioned above will find a small arrow marking the black lead's connector, and HP tells us that this arrow marks the positive connector of the power LED header. This made little sense to us since the wire next to it was red (despite my photo's color correction error). We followed HP's instructions, found the RGB controller unresponsive, and reversed the connector to fix the problem. Red is positive despite the manual's assertion.

We needed to dig in deep to mount our radiator in the Omen 45L's Cryo Chamber, and that begins with removing the plastic trim plate the surrounds the top-panel ports (two screws), and then removing the frame that encloses the radiator cage (six screws). The cage itself is secured with a screw near the front of each side and a tab at the rear, where removing those two screws allows it to slide forward a quarter-inch and be lifted away. We found the removal of the logo/port panel completely unnecessary despite its inclusion in HP's instructions.

Radiator coolant lines wrap around the back of the vapor chamber's air gap and rest within an around-14mm gap, which is large enough for both 3/8-inch open-loop tubing and the rubber hoses that come with most closed-loop coolers. HP advises that larger lines will fit if they’re squishy, but its instructions leave us stranded at the point where this little bridge piece must be removed. That's probably because it engages a tab on the inside of the back panel, and explaining how to extract and replace it (straight out the open side, straight in from that same side) would have made the firm liable to anyone who misunderstood the instructions.

With our full ATX motherboard mounted, we can see how anything larger might have made contact with the inset portion of the motherboard tray that's forward of the motherboard's front edge. Given the market for this case, we’ve no idea why HP didn't at least provide room for those somewhat rare but super-high-end 10.6-to-10.8-inch boards that usually carry an EATX label.

We discovered the interior light strip upon turning on our freshly built machine, and configured it to red.

Designed for an HP prebuilt Omen PC and downloadable from Microsoft Store, Omen Gaming Hub is an associated bit of software to use with the case. It takes over half a minute to load on our hardware; the load time seems a bit excessive when the only thing we’re using it for is RGB control, but it does that well, in addition to other, non-case things.

As for why we picked red, you be the judge. We think it looks pretty slick.

The only two cases we’ve tested that have used a separate cooling path for the CPU are the Omen 45L and the In Win N515, and these two are roughly matched in today's CPU temperature chart. Around 10° cooler than either the Hyte Y40 or Lian Li O11 Dynamic EVO, a look at the review for this test platform reveals a 2-to-4-degree advantage for both the Omen 45L and the In Win 515 when compared to the best of our more traditional cases.

We should mention that the reason HP's Omen 45L can function properly without so much as a single intake fan is that its exhaust fan is extraordinary by desktop PC standards: Operating at 3,400rpm, it outputs roughly twice the air volume at roughly four times the audible volume of a typical 1,200-to-1,400rpm exhaust fan. Our motherboard's CPU voltage regulator appreciates the extra airflow.

The lack of an intake fan did have some impact on GPU temperature, but the loss here is relatively minor with 4 degrees separating the entire field.

You’ll hear all that extra exhaust fan noise only if you stand behind the Omen 45L, as most other cases are primarily impacted by the noise of our graphics card's fans. It's still a raucous affair that could only be solved by enabling our motherboard's automatic fan controls, which in turn would have wrecked the Omen 45L's voltage regulator temperature win.

Because its exhaust fan can operate over a wider range of RPM than any of its competitors, we should probably ignore the case's voltage regulator temperature win and noise level loss in any further consideration of its performance. That leaves us with a CPU temperature that's matched by only one competitor, the In Win 515.

With that consideration in mind, you may be asking yourself whether the separate radiator cooling path of either the Omen 45L or the In Win 515 is worth the 2-degree cooling advantage, given that we could just mount the radiator to the front of our case if we wanted it to have the coolest air. We tried that and found that the GPU and voltage regulator temperatures went up by 3.8 to 4 degrees.

For those whose radiators cool the CPU, the Omen 45L's separate radiator cooling path is either saving you a couple degrees in CPU temperature or a few degrees in the temperature of non-CPU components when compared to more traditional cases. That's a fine point, to be sure. But if the look of the Omen 45L catches your eye, and you can handle the bulk and cost of a full tower that isn't especially equipped for oversize motherboards or loads of drive storage, the Omen 45L makes an impressive showing to the eye and the air.