Cooler Master HAF Stacker 935 - Greater than the Sum of its Parts

Cooler Master HAF Stacker 935 - The Stacker Reimagined

With the Cooler Master HAF Stacker 935, the company appears to have revived the defunct Stacker series. Although we can't pinpoint exactly when the old series was put into cold storage, our last experience with the Stacker series was back in 2004 with the . Fast forward a decade, we have the HAF Stacker 935, with a new feature that introduces the concept of modular expansion and thus making it a true Stacker. The new case also has the High Air Flow (HAF) design principles incorporated.

The HAF Stacker 935 is a full tower chassis that supports mATX, ATX, EATX motherboards. The Stacker 935 package actually consists of two separate casings, with the smaller HAF 915R stacked on top of the larger, mid-tower HAF 925 case. The HAF 915R only supports mini-ITX motherboards, and can be purchased separately as an add-on module, or as a stand-alone unit. Unfortunately, the HAF 925 isn't available as a separate component as it is only bundled with the HAF Stacker 935 product. Before we delve deeper, let us look at the specifications of the HAF Stacker 935 as a whole.

Since the HAF Stacker 935 is a combination of two casing structures and that the smaller unit can actually be purchased separately, we've spent some time assessing these case units separately, prior to using the HAF Stacker 935 as a whole. If you're someone planning to start from an average size system and work your way to an ultra-sized one in the future, our methodological assessment should help you better understand the different use-case scenarios of the HAF Stacker 935 casing system. Also, if you want to be ambitious and setup dual systems within the HAF Stacker 935, our segmented assessment will also give you a better idea of what's possible.

First up, we check out the HAF Stacker 915R component.

External Design & Features (HAF 915R)

The HAF 915R mini-ITX casing has rails that enables it to be attached to the mid-tower HAF 925 component. At a glance, we can see that the chassis boasts of good ventilation due to its metal mesh that covers a good part of it. The empty weight of the HAF 915R is listed as 5.7kg, which is rather heavy for its form factor class. Mini-ITX casings tend to tip the scale at around 3.5kg or so. The front of the chassis boasts of a mesh-covered facade for ventilation, with removable dust filters. Fret not if you think there are no ports or audio jacks, the removable I/O module is located on the mid-tower HAF 925 component. 

If you were to purchase the HAF 915R or HAF 915F separately (the "R" model refers to rear-mounted PSU, while the "F" model corresponds to a front-mounted PSU), they will come equipped with an I/O module since this chassis is designed for stand-alone use or even a stacked tower formed with multiple HAF 915 units. With regards to how the HAF 915 unit meshes with the mid-tower unit, we'll provide more details on that later.

The side panels of the mini-ITX chassis feature options for mounting side intake fans, and they also support a single radiator for liquid cooling systems. The exact dimensions of these components are listed in the table above. The panels have removable dust filters too.

From the rear, we can see the pair of expansion slots, and the option for mounting the standard ATX / PS/2 power supply unit at the top. Yes, we think it's a tad old-school. This will also limit your choice of CPU coolers that can be mounted if you plan to build a system out of it.

The bottom of the case boasts of a large opening with rubber grommets, and four smaller, identical opening that are without any covers. Obviously the HAF 915R unit that ships with the HAF Stacker 935 was designed to hook up with the mid-tower unit, hence it features these openings.

Interior Design and Features (HAF 915R)

The side panels of the HAF 915 case has thumbscrews that are all attached to the panels and helps prevent the loss of any of these screws. After removing the side panels, we see the spacious interior of the case. If you plan on setting up a Mini-ITX system, it is able to accommodate graphics cards that are as long as 14.17 inches (360mm). You can rest assure that this should fit almost any mainstream or enthusiast graphics card. In front, it has a removable 2.5-/3.5-inch drive enclosure, and it is able to fit up to three such drives. Above it, there is a 5.25-inch drive bay that comes with a convenient locking mechanism.

For those who wish to use the HAF 915R component as an expansion deck, the vast space within allows you to stack more drive cages from the HAF 925 mid-tower or mount huge water cooling radiators.

At the front of the chassis, there is a pre-installed 92mm intake fan. The I/O module, which houses the power and reset buttons, USB ports, and audio jacks, is located on the mid-tower 925 component. The module is removable and its transplant involves some re-routing of the module's cables.

Installation

For this portion of our write-up, we'll consider a standard system installation procedure with the HAF 915R case component. This would be useful for those intending to purchase only the HAF 915 unit or those who buy the HAF 935 but wish to start small, or for the more technically inclined folks, build dual systems within the HAF 935 (one in the 925 portion, and another in the 915). The latter will however involve some case modding to get it going unless Cooler Master can sell an additional I/O module to separately power the HAF 915 and HAF 925 portions. Are you listening Cooler Master?

Having established the motive, the general installation process of our test components was a straight-forward affair. With the bundled drive adapters, it was easy to fit our drives, and put them into their respective slots. The 3.5-inch drive snaps into place without the need for additional fastening screws. There are options for these screws but we found them unnecessary during our installation.

For 2.5-inch drives, the fastening screws are a must, and we used them to secure our SSD to the bottom of the adapter.

After sliding in the secured drive trays, we installed an ASUS BW-12B1ST Blu-ray ODD above the front intake fan without a hitch. It was a simple slide-and-lock affair. Following that, we installed the rest of our components, the ECS HDC-I/E-240 mini-ITX motherboard, the standard PS/2 ATX PSU, and an average sized 10.5-inch graphics card.

From the other side, we have a better view of the mini-ITX board and the top-mounted PSU. Since the PSU sits over the motherboard, the CPU cooler's maximum height cannot be greater than 80mm (3.1 inches).

During our installation exercise, we removed the I/O module from the HAF 925 component, and installed it above our ASUS Blu-ray drive.

With the side and front panels in place, we have the Cooler Master HAF 915R in its stand-alone mode.

Our Thoughts for the Stand-Alone HAF 915R

The HAF 915R is a hefty mini-ITX casing. Its somewhat tool-free design made our installation a breeze, and the attached thumbscrews of its side panels are a nice touch. A point to moot is the position of the PSU as it sits directly over the mini-ITX board. Hence, it will restrict the height of the CPU cooler. Otherwise, the HAF 915R is a functional, well-ventilated (albeit deep) mini-ITX chassis ideal for users who will definitely outfit the system with powerful graphics cards or see an opportunity to expand the system's functionality by stacking more HAF 915 units in the future.

Design and Features (HAF 925)

The larger part of the HAF Stacker 935 is the mid-tower 925 component. We call it a component as it isn't available for sale, unlike the HAF 915R chassis reviewed earlier. The HAF 925 is bundled with the HAF 915R, to make up the modular, full tower HAF Stacker 935. For the purpose of dissecting the mid-tower portion of this chassis system, we'll be assessing the HAF 925 aspect from the point of view of a HAF Stacker 935 purchaser who's interested in modular expansion, but would like to start off with the mid-tower portion and slowly expand to occupy what the HAF 935 offers in its entirety.

From this angle above the case, we can see the openings to mount a trio of 120mm outlet fans. Though there are three openings, the casing's official specifications state that it fits up to a pair of such fans.

Note that the fan openings are flanked by a pair of rails, which allow the HAF 915R to slide into place. Since the HAF 935 is made to pair both the HAF 925 and HAF 915R components, the top of the mid-tower is left open by default. We'll show you how the HAF 915R slides into place in the following section of our article.

The rear of the mid-tower section reveals eight expansion slots, a 140mm rear outlet fan, and a triplet of rubber grommets for the cooling pipes of external radiators. There is also an additional expansion slot for mounting extra USB/eSATA ports from your motherboard's expansion header(s).

The bottom of the HAF 925 has a removable dust filter for its intake vents. The large rubber grommets cover openings that allow accessories to be extended from a bottom-mounted HAF 915 chassis. The feet of the mid-tower HAF 925 have to be removed first, in order to expose its mounting rails, which are identical to the ones found at the top of the HAF 925.

Interior Design (HAF 925)

The case is able to accommodate motherboards of the following forms factors; EAXT, ATX and mATX. The motherboard tray has a large cut-out for mounting aftermarket CPU coolers. There are also rubber grommets for cable management.

From this perspective (below photo), we have a clearer view of the bundled, 140mm outlet fan. At the bottom, you'll notice there are four rubber pads for the power supply unit (PSU) to sit on.

To the front, there are two removable 3.5-inch drive enclosures. Each enclosure has three drive adapters that allow for mounting of 2.5-inch drives. Above the enclosures, there are three 5.25-inch drive bays, each with a self-locking mechanism. The options for installation of such drives are identical to the HAF 915R mini-ITX counterpart.

With its front panel removed, we see the options for installing a pair of 120mm intake fans; with the two HDD enclosures removed, there is space to fit a single 240mm radiator. We also see the I/O module at the top of the facade. There is a power switch next to the audio jacks. A pair of USB 3.0 ports (in blue) break the succession of a pair of USB 2.0 ports. The I/O module has a grounding cable, but a reset button is sadly absent in its lineup.

The motherboard tray has an option to mount a 2.5-inch drive below its CPU cooler cut-out. At a glance, we do find the cable clearance at the tray's rear a little limited.

Installation

For the installation procedure, we used an additional graphics card, the Sapphire Vapor-X R9 270X. The installation went without a hitch. With the cable management cut-outs through the help of rubber grommets, our power and data cables were neatly tucked away.

After our cable management efforts, we measured a cable clearance of 16mm (0.6 inches) between the rear tray and the side panel; as such we felt that an additional allowance of 2mm would have made cable management easier to tackle.

The top panel was cannibalized from the HAF 915R mini-ITX chassis as the HAF 925 doesn't come with a top panel. Additional cooling fans can be added to the front or to the top of the chassis. Hence, the facade of the case, as well as the top panel, features the black metal mesh for ventilation.

The tinted windows added a nice touch of mystery to what powerful PC components laid beyond.

The other side panel has a matte finish that doesn't attract fingerprint smudges. The removable feet of the chassis added stature to the entire chassis, and we found the mid-tower 925 to be an imposing one, with a height of 508mm (20 inches).

Our Thoughts on the HAF 925

The mid-tower HAF 925 case is well-ventilated with a simple front to rear airflow system. Hot air can also be expelled from the top when additional cooling fans are mounted. It also presents many options for liquid cooling kits. Unlike the mini-ITX HAF 915R, the HAF 925 didn't face the same CPU cooler height constraints, and according to the manual, the larger chassis is able to fit coolers as tall as 180mm (7.08 inches). There was only one main area of improvement and that's to create more allowance for cables at the back of the motherboard tray. Perhaps the designers can take a leaf out of Cooler Master CM 690 III's book as it features a stamped side panel that allows just that.

Stack Them Up for HAF Stacker 935

In our final page of assessment, we''ll look at a typical HAF Stacker 935 user and how he or she might segregate their components across. To construct the HAF Stacker 935, we had to slide the HAF 915 unit onto the top of the HAF 925 mid-tower chassis. The HAF 915 slides in from the rear, and it is secured with four mounting screws from the side. The HAF Stacker 935 is essentially a mid-tower 925, with an expanded loft in the form of the HAF 915R.

Installation

Next we proceeded with the installation of our components. We decided to make the top part of the HAF Stacker 935, a repository for storage drives. Since hard drives heat up quickly when the system is running, it makes sense to keep them separated at the top, away from the rest of the PC components.

To facilitate this, we removed the pair of 3.5-inch HDD enclosures from the HAF 925 so that there is unobstructed airflow towards the rear of the chassis. It also creates more space to accommodate extra large graphics cards with large custom coolers. We placed one of them at the top half (the HAF 915 unit) so that it can hold a total of six storage drives.

Besides the storage drives, the rest of the PC components were installed in the mid-tower portion of the Stacker. Since the storage drives were at the top, note that the SATA power and data cables had to be stretched and routed accordingly. Cooler Master has provided a SATA power connector extender to reach the SATA power connectors from the bottom-mounted PSU. This can help you route your SATA power cables behind the motherboard tray to reach the top mounted 'storage unit'. SATA data cables are however not long enough to be routed at the back, but they are are slim enough that you can still run them across the case within the main compartment and not mess up the air flow.

If for some reason, a top mounted 'storage unit' isn't feasible, you can easily consider a bottom-mounted placement. That way, most of the cabled will surely be within short reach between the main mid-tower unit's power supply and SATA connectors on the motherboard.

Affixing the side and front panels to complete our installation exercise, we found the HAF Stacker 935 standing at a height of 745mm, which is even taller than the NZXT Phantom. The latter stands at 627mm and is one of the tallest casings that we have reviewed recently. Of course, seeing that the HAF Stacker is more like two case units sold as one, it's height is inevitable.

However, this isn't the limit for the HAF Stacker 935. Since it is compatible with the HAF 915R or HAF 915F, an additional mini-ITX unit can be added to the base of the HAF Stacker 935 for housing more components, like the radiators of the liquid cooling kits. Thus, the maximum conceivable height of the Stacker 935 can be boosted by an additional 248mm to 993mm! If the user needs to mount more than two HAF 915 components, which this modular system can accommodate, we can't quite imagine what the additional space might be used for. Perhaps a tool box storage disguised inside a mini-ITX modular unit or a unit to hold spare parts? The sky's the limit it seems.

Another observation made is the possibility of housing two separate PC systems in a single HAF Stacker 935. The HAF 915R will house a mini-ITX system; while the mid-tower 925 houses another. And they can co-exist in the HAF Stacker 935. A possible scenario would be the top mini-ITX system functioning as a HTPC, and the mid-tower system taking the role of a gaming PC. This will however require some case modding know-how, unless Cooler Master can retail the I/O module separately which would solve all the trouble.

Conclusion: A Towering Hunk

The Cooler Master HAF Stacker 935 has a suggested retail price of S$269, but it can easily be found from as low as S$238, which is slightly lower than those ultra-sized full tower casings like the NZXT Phantom and the NZXT Switch 810 Special Edition The latter chassis cost almost S$300 apiece. Hence, the HAF Stacker 935 is attractively priced. As a whole, it allows the system builder to put together a full tower system with sufficient space for large graphics cards and CPU coolers. On top of that, the case is well-ventilated, with many options for both air and liquid cooling.

However, one of its drawbacks is its weight that tips the scales at 15.6kg, even when it is empty. Hence, with our installed components, we estimated its entire weight to be approximately an unyielding 20kg! Therefore, it would be good if Cooler Master had included casing feet with caster rollers that can assist the rig's ease of mobility and handling.

On the other hand, its greatest advantage is its modular nature. Users can choose to grow into the full size and capabilities of the HAF Stacker 935 gradually with its flexible usage of either the mini-ITX HAF 915 or mid-tower HAF 925 or even both (with modifications). Advanced enthusiasts can immediately take full advantage of the HAF Stacker 935's modular nature and even expand upon it endlessly with multiple HAF 915 case add-on units.

For builders who want to start small, but have grand plans for later, they can consider purchasing a HAF 915 mini-ITX chassis for S$119. Like the HAF Stacker 935, the HAF 915 supports modular stacking, and it can be expanded by simply adding one or more HAF 915 chassis units. To walk the middle path, it would be ideal if Cooler Master can make the HAF 925 mid-tower available as a standalone component. It is a well-ventilated case with many options for air and liquid cooling. If the owner decides to invest in a system upgrade, the HAF 925 can be quickly transformed into a HAF Stacker 935, with the addition of a HAF 915 unit.

In conclusion, we find the HAF Stacker 935 a feasible solution for system builders who enjoy its modular feature, regardless of its bulk or heft. It's the very strength of this chassis that makes the HAF Stacker 935 greater than the sum of its parts. For other builders who are set on their computing requirements, you can opt for a more compact non-expandable mini-ITX chassis like the recently launched Corsair Obsidian Series 250D for small form factor computing. Else they could settle for the aforementioned ultra casings along with the Cooler Master HAF Stacker 935 to build full tower systems right out of the box.

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