Cooler Master Cosmos II Full-Tower Case

Cooler Master released the Cosmos Chassis what seems like so long ago, but it to this day is still a widely used and modified platform because of its huge size and great liquid cooling compatibility. We all knew it was only a matter of time before Cooler Master refreshed the line and gave us a new offering. Today we are going to take a look at that new offering, the Cooler Master Cosmos II. Read on to see what this chassis has to offer and why you want it!

SUPPLIED BY: Cooler Master
PROD LINK: Cosmos II Product Page
PRICE: $349.99 @ NewEgg
Price is at the time of testing!

Cooler Master Cosmos II Full-Tower

When we first received the case we were amazed by the sheer size of the box, and the weight at a not so scant 50 or so pounds. After dragging it inside we made quick work of removing the packaging to get a glance at the chassis itself. Dense Styrofoam is used to hold the Cosmos II in place during shipping. We can also see that it is tucked inside a large clear bag, which is used to help keep it from acquiring scratches during the boxing and shipping processes, but who cares about the packaging we want to see the case.

Cooler Master Cosmos II Full-Tower

Here we can see some of the sleek styling of the case which carries from the front around the side as well, making for an overall clean appearance while still maintaining a racy look with the louvered vents on the side panel.

Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower

Moving on to the upper front section, we see the front panel connections which are plentiful. It has 4 USB 2.0 ports, a pair of USB 3.0 ports (fed by an internal 20 pin header), a single e-SATA port and a pair of audio ports to round out the connectivity. After sliding back the upper cover we get a look at the front panel control center, which houses the standard power and reset controls but also includes the internal fan controller.

Cooler Master Cosmos II Full-Tower

The fan controller is quite nice for a built-in unit. It has multiple channels which are each set for a specific area of the chassis and be controlled independently of each other. Do keep in mind that each fan lead from the controller is marked for its designated section. You will want to pay attention to which fans you’re connecting to which leads, otherwise when adjusting the fans via the controller you could end up adjusting the wrong fans. Another nice feature of the controller is the inclusion of LED controls and wire leads for multiple fans pending the correct fans are used in conjunction with the controller. The controller surface itself is a metallic surface with a solid feel similar to what we had seen on old Motorola Razor phones for those of you who remember those. This selection of control surface is nice and gives it a much more solid feel than many of the plastic press button switches we have on cases these days.


  • Stylish and streamlined race-car inspired design
  • Brushed aluminum and steel for strength and elegance
  • Airflow Optimized Design
  • Supports up to 10 fans and 13 HDDs (2 from X-dock)
  • Supports 4 Way SLI/CF
  • Supports XL-ATX / SSI CEB / SSI EEB boards
  • Advanced Control Panel includes 4 channel fan speed control
  • Rich I/O support: USB 3.0 x 2, USB 2.0 x 4, e-SATA x 1, Audio In and Out

Cosmos II Specifications
Model RC-1200-KKN1
Available Color Midnight Black
Material Exterior: Aluminum, Mesh, Synthetics;
Interior: Steel-Alloy, Synthetics, Rubber
Dimension (W / H / D) 344 x 704 x 664 mm / 13.5 x 27.7 x 26.1 inch
Weight 22kg / 48.5 lb
5.25″ Drive Bay 3
3.5″ Drive Bay 13 (2 from X-docking with key locks, 5 HDDs in the Middle cage, 6 HDDs in the bottom cage)
2.5″/3.5″ – SATA HDD Drive Bay 11 (converted from 3.5″ cages)
I/O Panel USB 3.0 x 2, USB 2.0 x 4, e-SATA x 1, Audio In and Out
Expansion Slots 10+1
Cooling System Front: 200mm LED fan x 1, 700 RPM, 19 dBA(converted from 120/140mm x 1)

Top: 120mm black fan x 1, 1200 RPM, 17 dBA
(optional: 200mm fan x 1 / 140mm fan x 2 / 120mm fan x 3)

Rear: 140mm fan x 1, 1200 RPM, 19 dBA

Side: 120mm fan x 2 (optional)

HDD: Mid.HDD: 120x25mm fan x 1 (optional); Bottom HDD: 120mm fan x 2, 1200 RPM, 17 dBA

Power Supply ATX PS2 / EPS 12V (optional)
Warranty 2 years
UPC Code 884102014857

Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower

Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower

Moving down the face of the case we see a smooth front edge, which is actually a door covering the front 5.25″ bays. The front door is actually a rather cool design, it slides downward with just enough resistance so that you know it won’t lower itself on its own. Once lowered we see all of the drive mounting options, there are a total of 5 bays on the front panel 3 of which support 5.25″ devices and 2 that are hot-swap lockable HDD bays. On the lower section of the front panel, we have the removable panel which also houses the dust filtration. Tucked in behind the front panel we have the pre-installed 200mm LED fan which handles some of the air inlet duties for cooling the massive Cosmos II.

Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower

Looking over the top, we see the dual carry handles at the top which are very strong and built to handle carrying a fully loaded system. If you’re planning to carry chassis from the handles, ensure that both handles are used to keep system level and avoid running into corners or walls like I did the first time carrying it. The top screened area is actually a full panel that drops into place and is held there with a single thumbscrew. Removing the thumbscrew allows the user to lift panel out, which gives them access to fan/radiator mounts located underneath it. This is a nice way of addressing the installation headaches that can occur on other designs. Now this design is setup so that radiators can be mounted with the fans above the top panel but below the cover, while this will work with most scenarios it will not work with all and we will get to that during the installation portion of this review.

Cooler Master Cosmos II Full-Tower

On the rear, we find more than enough expansion slots to house any board from Micro-ATX, E-ATX, XL-ATX and bigger. This means 4 way SLI or Crossfire capable systems should have no issues with the 10 expansion slots available. There is also another expansion slot mounted perpendicular to the others, which is used for mounting other accessory expansion cards. The Cosmos II comes with a pre-installed rear 140mm exhaust fan, but also allows for the installation of 120mm fans. Above the rear fan are the three pass-through holes which are meant to allow the user to mount external radiators for their liquid cooling setup. Given the massive size of the case though, I think you would be hard-pressed to find a way to need externally mounted liquid cooling as the case is big enough to handle most any loop size or design.

Cooler Master Cosmos II Full-Tower Cooler Master Cosmos II Full-Tower

At the lower edge below all of the expansion slots, we have the PSU area which has its own bracket held on with 4 thumbscrews. This was done to give just a little more room for the adjacent drive cages by moving the power supply outside of the case by a couple of inches. To continue the trend of a dust-free system we find another removable filter at the bottom below the PSU, which is done to ensure that minimal amount of dust and dirt gets into the system at all, which is always a good thing.