A Closer Look - Adjusting Interior

At this step, we usually dive into the assembly process, but the be quiet! Dark Base Pro 900 has some serious surprises up its sleeve. I was teasing you all along with the unique layout in the rear of the chassis. Knowledgeable readers may have noticed that a radiator setup in the ceiling would interfere with the rear fan. be quiet! solves this issue by allowing you to adjust the height at which the motherboard tray is placed. There are three thin pieces you may remove in the rear - two mesh variants in the bottom and a solid one in the top. Thanks to the removable motherboard tray, which comes with three sets of mounting holes on the edge, you may then adjust the height of the tray by placing it where you would want it with the small pieces set to fill the gaps.


By default, there is a small solid piece of the motherboard tray in the top, which leaves around 30 mm of space between ceiling and motherboard tray - enough to go for fans that are mostly 25 mm high.


But you may move one or both of the metal mesh pieces above the motherboard and secure the tray itself below them. This extends the available space to 75 mm, which means that you could install a thick radiator and fans here without issue. This level of engineering comes along once every few years, and it is great to see such a beautiful execution.


That also solves the mystery of why the PSU bay has been detached from the rear and moved backward. If you place the motherboard tray all the way down, a normal PSU would no longer fit. The one downside here is that you will lose access to the bottom two PCIe slots of a motherboard. However, this should still give you access to two PCI x16 slots for a potent dual-GPU rig.