Unknown Cooler Master MasterBox 600 Review UK 2026

After twelve years of building PCs, I've got a pretty good nose for cases that are going to cause problems before I even open the box. You know the type. Sharp stamped edges that take a chunk out of your knuckle when you're routing the 24-pin. Rear cable channels so shallow the side panel won't close without a fight. PSU shrouds that look great in photos but leave you with nowhere sensible to hide a modular cable bundle. I've built in enough of them to know that a case isn't just a box. It's the thing you're going to be wrestling with for three or four hours on build day, and then living with every time you need to swap a drive or add a fan.

The Cooler Master MasterBox 600 sits in that mid-range bracket where things get genuinely interesting. You're past the budget tier where compromises are expected, but you haven't crossed into the territory where the case costs more than some of the components going inside it. For that kind of money, you want proper airflow, sensible cable routing, and a build experience that doesn't make you question your life choices. I've had this case on the bench for several weeks now, running a full system build through it and living with the results. Here's what I found.

This is my full Cooler Master MasterBox 600 Review UK (2026), covering everything from clearances and cable management to airflow and build quality. If you're trying to decide whether this is the right case for your next build, read on.

Fan support is where things get interesting. The front panel supports up to three 120mm or two 140mm fans, the top takes up to two 120mm or two 140mm, and the rear has a single 120mm exhaust position. Cooler Master includes three 120mm fans in the box, all mounted at the front as intake, which is a sensible default configuration. Radiator support covers 360mm at the front, 240mm at the top, and 120mm at the rear, so you've got real flexibility for cooling configurations.

Drive storage is handled by two 3.5-inch bays and two 2.5-inch dedicated mounts, plus additional 2.5-inch mounting positions on the back of the motherboard tray. The PSU shroud covers the bottom section neatly, and there's a removable dust filter underneath for the PSU intake. Front I/O includes two USB 3.0 Type-A ports, one USB 3.2 Gen 2 Type-C, and a combined audio jack. That Type-C port is a proper Gen 2 connection, not a downgraded Gen 1 with a Type-C connector bolted on, which matters if you're plugging in fast external drives or modern peripherals.

The footprint feels well-proportioned in person. Photos can make cases look either massive or tiny depending on the angle, but this one is genuinely a normal-sized mid-tower. It'll sit next to a monitor without looking out of place, and the tempered glass panel faces left, which is the standard orientation for most desk setups. The top of the case has a mesh panel for exhaust, which is good for thermals but does mean it'll collect dust if you've got the case on a desk rather than a floor. Worth keeping a can of compressed air handy.

The rubber feet are decent. Four of them, reasonably grippy, and they keep the case stable on both hard floors and desk surfaces. Nothing revolutionary there, but I've had cases with feet that might as well be decorative, so it's worth mentioning when they actually do their job. The overall silhouette is clean without being flashy. If you want a case that looks professional rather than aggressively gamer-y, this fits the brief.

I built this review system with a standard ATX board and the fit was clean. The motherboard tray has good cutouts for cable routing behind the board, and the CPU backplate cutout is large enough to accommodate most aftermarket cooler mounting hardware without removing the motherboard. That's a detail that sounds minor until you're trying to swap a cooler and realise you'd need to pull the whole board to get to the backplate. Cooler Master has clearly thought about this.

The standoffs themselves are brass and feel solid. I've had cases where the standoffs strip after a couple of builds, which is genuinely annoying if you're using the same case for multiple projects. These feel like they'll hold up. The screw holes in the tray are cleanly punched with no burring, which keeps things aligned properly when you're seating the board. Small detail, but it matters for getting a clean build.

There's no vertical GPU mount included in the box, which is a slight omission at this price point. Some competing cases include a riser cable and vertical bracket as standard. If you want to show off your GPU through the glass panel in a vertical orientation, you'll need to buy a separate riser cable and bracket. Not a dealbreaker, but worth knowing if that's something you were planning on.

The PCIe slot covers are the standard tool-required type, not tool-free. They're held in with thumbscrews rather than a latch mechanism. Honestly, I don't mind this. Tool-free slot covers can rattle, and for something you're only moving occasionally, a thumbscrew is fine. The covers themselves are solid steel with no flex, and they align properly with the rear panel without any gaps. GPU installation was straightforward, with enough room to get your hands in and seat the card without contorting yourself.

For front-mounted 360mm AIOs, the pump head clearance is worth checking against your specific board. Most modern boards have the CPU socket positioned far enough from the front of the case that a 360mm radiator at the front won't cause any interference with the pump head or tubing routing. I ran a 240mm AIO in the top position during testing and had no issues with RAM clearance. The top radiator mount sits high enough that even tall RAM heatspreaders shouldn't cause problems, though if you're running something like Corsair Dominator Platinum with very tall fins, double-check the measurements.

Rear exhaust supports a single 120mm fan or a 120mm radiator for a slim AIO. That's standard for a mid-tower. The rear fan position is pre-installed with one of the included 120mm fans as exhaust in some configurations, but in the default box setup all three fans are at the front as intake. You'll want to add a rear exhaust fan if you're not running an AIO with a rear radiator. Cooler Master's own product page for the MasterBox 600 has the full radiator compatibility matrix if you want to cross-reference your specific cooler.

The two dedicated 2.5-inch bays are on the back of the PSU shroud, mounted vertically. They're tool-required, using standard screws, which is fine for drives you're not swapping regularly. There are additional 2.5-inch mounting points on the back of the motherboard tray for SSDs you want to hide away. In total, you can fit a reasonable number of drives without running out of mounting options, which covers most builds that aren't doing serious NAS-style storage.

One thing I'd flag: the 3.5-inch bays do take up some of the cable management space behind the PSU shroud. If you're running a lot of drives and a fully modular PSU with a thick cable bundle, it can get a bit tight back there. Not impossible to manage, but worth being aware of when you're planning your build. I'll cover this more in the cable management section. For most people running one or two HDDs alongside a couple of SSDs, it's a non-issue.

There are Velcro straps pre-installed at several points along the back of the motherboard tray. Three of them, positioned at sensible intervals. Not every case includes these, and the ones that do sometimes put them in positions that aren't actually useful. These are in the right places. The cable routing holes in the motherboard tray are all grommetted with rubber, which keeps things looking tidy and prevents cable chafe against sharp edges. The grommets are a proper rubber compound, not the cheap foam type that falls apart after a year.

The 24-pin motherboard cable routes cleanly through a cutout on the right side of the tray, and the CPU EPS cable has a dedicated routing channel along the top of the tray behind the motherboard. This is important for keeping the EPS cable out of the airflow path and away from the CPU cooler. The GPU power cables route through a cutout in the PSU shroud, which keeps them hidden until they emerge at the GPU. Overall, the cable management design is thoughtful. I've built in cases at twice the price with worse routing options.

The three included 120mm fans are Cooler Master's own units, running at a rated 1200 RPM. They're not the quietest fans in the world at full speed, but they move a decent amount of air. In practice, connected to a motherboard fan header with PWM control, they'll sit at lower speeds during light loads and only spin up under sustained gaming or rendering workloads. During my testing with a mid-range CPU and GPU combination, temperatures were well within acceptable ranges with the stock fan configuration. Adding a rear exhaust fan improved things slightly, but the default three-fan intake setup is genuinely functional rather than just a marketing checkbox.

The dust filters are worth calling out specifically. There's a magnetic filter on the front panel that pulls away cleanly for cleaning, a filter under the PSU intake, and the top mesh panel has a removable filter as well. Three filters, all accessible without tools, all properly sized to cover the relevant openings. This is how it should be done. I've seen cases with filters that cover only half the intake area, or filters that require you to remove a panel to access them. These are all easy to pull out, rinse under a tap, and put back. That matters for long-term maintenance, which is something people don't think about enough when they're buying a case.

The USB 3.2 Gen 2 Type-C port is the standout here. At this price point, some manufacturers still include a Gen 1 Type-C port, which caps out at 5Gbps. The Gen 2 connection runs at 10Gbps, which makes a real difference if you're using fast external SSDs or connecting modern devices. The internal header requires a USB 3.2 Gen 2 Type-C header on your motherboard, which most current mid-range and above boards include. Worth checking your specific board's header layout before assuming it'll work. The USB Implementers Forum has the full specification breakdown if you want to understand the difference between Gen 1 and Gen 2 in detail.

The two USB 3.0 Type-A ports are standard and work exactly as expected. The combined audio jack is a 3.5mm TRRS connector that handles both headphone output and microphone input through a single port. Some people prefer separate headphone and mic jacks, and I get that, but a single combined jack is increasingly the norm and works fine with modern headsets. The audio quality through the front panel depends heavily on your motherboard's audio implementation, as always. The cable connecting to the HD Audio header is long enough to route cleanly to most motherboard positions.

The tempered glass side panel is 4mm thick and attaches with four thumbscrews at the corners. It sits flush with the chassis frame with no visible gaps, and the thumbscrews have rubber washers to prevent cracking the glass. The panel itself is clear rather than tinted, which gives you a clean view of the components inside. Some people prefer a slight tint to hide cable management imperfections, but clear glass shows off a well-built system properly. The right-side steel panel attaches with two thumbscrews at the rear and slides back before lifting off. It's a standard mechanism that works fine.

Edge finishing is good throughout. I ran my hands along all the internal edges during the build and didn't find any sharp points or burrs. The stamped cutouts in the motherboard tray are clean, the cable routing holes are properly grommetted, and the fan mounting holes are deburred. This sounds like a low bar, but I've genuinely cut myself on cases in this price range before, so clean edges are something I actively check. The finish on the exterior is a matte black powder coat that resists fingerprints reasonably well. It's not completely fingerprint-proof, but it's better than a glossy finish.

Where the MasterBox 600 wins is the combination of three included fans, the Gen 2 Type-C front port, and the 410mm GPU clearance. For a build where you want to get up and running without immediately buying additional fans, the included trio is genuinely useful. The Fractal Pop Air will require you to add a third fan if you want full front coverage, which adds to the total cost. The NZXT H5 Flow has excellent build quality but the premium you pay for the brand name is real.

The Corsair 4000D Airflow is another case that comes up in this conversation. It's a proven performer with good airflow and a solid build experience, but it typically costs a bit more and includes only two fans. The MasterBox 600 offers comparable airflow performance with more fans included out of the box. For a budget-conscious builder who wants a proper mid-range case without spending extra on fans immediately, the MasterBox 600 makes a strong argument.

Is it perfect? No. The lack of a vertical GPU mount is a miss for a case at this price. The rear cable space is adequate but not generous, and if you're running a lot of drives alongside a thick cable bundle it can get a bit cramped. And the included fans, while functional, aren't the quietest. If you're building a near-silent system, you'll probably want to replace them with something like Noctua or be quiet! units. But these are relatively minor complaints against a case that delivers solid performance and a good build experience at a mid-range price point.

Who should buy this? Anyone building a mainstream gaming or workstation PC who wants a case that performs well thermally, has room for proper cooling, and won't make the build process miserable. It's particularly good value if you were planning to buy three 120mm fans anyway, since they're included. Who should skip it? If you need a vertical GPU mount, look elsewhere or budget for a separate riser. If you want the absolute quietest possible system, the included fans will need replacing. And if you're building a compact system, this is a full mid-tower and there are better options in the mATX or ITX space.

At its current mid-range price, the MasterBox 600 represents solid value. It's not the cheapest option in this category, but it's not trying to be. It's a case that does what it promises, built to a standard that should last through multiple component upgrades. For most builders, that's exactly what you need. You can check the current UK price below.