A Closer Look - Inside

To gain access to the interior, simply remove the two thumbscrews holding each side panel in place. As expected, the interior of the Cosmos SE is all-black to go with the overall look of the chassis. Cooler Master has also included plenty of possibilities to secure unwanted cables onto the backside of the motherboard tray, and there is a large opening for access to the underside of the motherboard's CPU area. The motherboard tray even has grommet-covered holes to route cables through. As a small extra, secondary, smaller openings can also be found, giving the user as much flexibility as possible.


There is around 30 mm worth of space between the motherboard tray and the side panel. This is not counting the added width due to the extrusion of the side panel. Including the extrusion, you should end up with up to 40 mm in the middle. Cooler Master advertises the chassis with the ability to hold up to 18 SSDs, which, while unlikely, is still a unique selling point some scenarios may require. Two of these slots can be found on this side of the case, with one of the spots on the side of the external drive bays and the other all the way on the bottom where the externally accessible 3.5" bays are.


Taking a closer look at the interior, the aforementioned two hard-drive bays on the very bottom are supposed to face toward the front at all times. It would have been nice to see some SATA power and data brackets here, which would have made these two slots truly hot-swappable. As it stands now, installing or removing a drive here will still require you to take the side panel off. Above that are the six internal hard-drive trays. Each of these trays, including the pair facing out the front at all times, can either hold a single 3.5" or two 2.5" drives, thanks to their shape and spacing. This means that up to 16 2.5" drives will fit in here. Include the two on the side and we reach the advertised count of 18 hard-drive bays. There are then two external drive bays in the top. These do not come with an ineffective plastic locking mechanism. Cooler Master instead still counts on the use of screws to hold 5.25" devices in place. Remember: The exterior hints at 3 external 5.25" bays, but there are only two out of the box. This is due to the modular nature of the front, so let us take a look at it.


The first step to creating a front-mounted drive bay is the removal of the entire front cover. Doing so reveals the two 120 mm, blue LED-equipped fans. You may place a 360 mm radiator in the front if you really want to instead, but will end up blocking off most of the bays in the process. To free up the third drive bay, the top fan needs to be removed first.


Once removed, the hard-drive trays of the chosen bays need to be taken out as well. Cooler Master has designed the interior of the Cosmos SE in a way that allows each module to hold two drive bays, be it 2.5" or 3.5" hard drives, or 5.25" drives. There are a total of three ways to set up these modules. The first, and default, is as internally accessible hard-drive bays. The second setup allows you to pull the hard drives out the front of the chassis instead. We have seen this type of modularity in the CM Storm Trooper already, but Cooler Master has gone one step further and engineered the two wall panels of each pair of drive bay in a way that allows you to remove all plastic elements completely, which allows you to turn these walls around. Doing so turns the module into fully functional external 5.25" bays. As you are forced to transform two bays at a time, but only have one additional external drive bay due to the design of the front cover, you will loose one spot for hard drives in the process. Cooler Master should have maybe gone with four external bays instead, but one cannot comment on how the chassis would look in such a scenario. The fact that Cooler Master has included such integrate bays shows the level of engineering that went into the design of the Comsos SE.


Things are much simpler in the rear, but not less effective. The bottom power supply bay offers two foam-covered rails on which the installed PSU will rest. Above that are the seven motherboard expansion slots. Each slot is protected by an individual, re-usable cover held in place by black thumbscrews. The two additional slots can easily be removed from outside the case as the screws have been placed behind the case walls in the rear. Above that is the aforementioned 120 mm exhaust fan. The Cosmos SE cannot take a 140 mm unit here, which also means that you have to watch the height of your installed air coolers, especially if using a tower-type cooler.


You will find the fourth and last fan within the Cosmos SE pre-installed to the ceiling of the case. This one is a 140 mm version, and there are also enough mounting holes here for a 240/280 mm radiator to be installed. Doing so will block off the top external drive bay, though. So, the Cosmos SE can hold a 120 mm + 240/280 mm + 360 mm liquid-cooling setup, which is quite impressive for a chassis of its size.