A Closer Look - Inside

Before we dive into the interior, let's take a closer look at the solid side panel. As you can see, sound-dampening material has been placed across most of the surface area, and the aforementioned air duct offers mounting holes for two 120 mm fans. However, there is not really enough space behind the motherboard tray to place fans here. The simple reality is that be quiet! has designed the panel so that it may be used on both sides of the chassis. Those who buy the variant lacking the glass side panel will simply see one of these solid units flipped and installed in its place. The duct can be taken off the panel and rotated 180° so that the brand logo is displayed with the right side up.


While the internal layout of the Dark Base Pro 900 is quite traditional, the level of engineering and design that has gone into it will put some long-time chassis brands to shame. be quiet! has done an excellent job in engineering as much of the enclosure themselves instead of using off-the-shelf tooling. As we are reviewing the variant with orange color accents, those continue inside the frame with the various rubber grommets and bits.


Besides the large opening in the motherboard tray, you will also find a fan PCB here with which you may control up to seven fans - three PWM and four 3-pin ones. Naturally, you should be able to use splitters to connect even more if you like. There is also a 2.5" frame to allow for a single such drive to be placed here, behind the motherboard tray. The seven individual hard-drive trays are secured with three thumbscrews each, which in itself is quite impressive. If you look closely, you can see that there are two empty openings at the very top where the 5.25" cage is located.


Looking at these bays from the opposite side, you can clearly see that the orange grommets are used to hold the drive in place and act as an anti-vibration mechanism at the same time. The simple but effective 5.25" cage above these utilizes thumbscrews to hold drives in place. You could remove it to make way for additional hard drives here, but would need to source the HDD cages separately.


Alternatively, you could take out the 5.25" cage and still use two of the removed HDD cages in the very top alongside a 280 mm or 360 mm radiator should you want to use potent liquid cooling in the front. If you opt for a 280 mm variant, you will also have enough space for a 280 mm unit here. Unfortunately, the mounting holes will prohibit you from going for a 240 mm radiator. Regardless of this, I can see some serious high-end builds with three potent radiators in one or multiple loops present within the be quiet! Dark Base Pro 900.


Turning our focus to the rear, the PSU bay has been moved away from the rear by a bracket. Out of the box, this contraption is about an inch away from the rear metal-mesh wall, but you may move it around thanks to the additional screw mounts on the floor of the chassis. Above that, you will find the eight expansion-slot covers, each held in place by a thumbscrew. If you look closely, you will also see some orange rubber elements and black screws on the frame of the chassis. Looks like the motherboard tray can be taken out of the chassis. In the very top, the 140 mm exhaust fan is once again of retail quality (be quiet! SilentWings 3) so that you may simply buy additional ones of the exact same model to extend the cooling capability of the Dark Base Pro 900.


In the ceiling, looking out from the inside, you will notice that the top cover is lined with sound-dampening material as well. There are so many cutouts in the ceiling that I had to double check on all the possible configurations here. In fact, you can install any radiator of up to 360 mm or 420 mm in size here, but you may have to sacrifice the top 5.25" bay to make room. Regardless, for those who want to go all out on liquid cooling, that should be no deal breaker at all.


Last but not least, the Qi charger consists of an intricate, circular PCB right below the plastic cover. There are two leads that supply the unit with power which is then passed on to the mobile device wirelessly.


Besides that, all the cables within the be quiet! Dark Base Pro 900 are of the standard variety. You will find a SATA power connector and the 4-pin PWM fan connector for the PCB here as well.