Getting inside the Define R5 is a little different than with other cases I've tested. The left side panel is secured with both thumbscrews and a push-to-release latch, while the right side panel sticks with a pair of thumbscrews. For both side panels, Fractal Design has fixed the one thing that I hate about the Obsidian 450D (and many other enclosures). Instead of the usual tongue-and-slot system that has to be positioned just so before sliding home properly, the Define R5's side panels only need to clip in at the front of the case before they can be secured. Bravo, Fractal.
The Define R5's motherboard tray is pretty conventional by modern standards, with the requisite set of rubber grommets ringing its border. Interestingly, the motherboard tray is recessed a little bit, which helps to explain the R5's ability to swallow 180-mm-tall CPU coolers. The motherboard tray also features an enormous cutout to facilitate the installation of CPU cooler backplates.
There's plenty of space for cable routing behind the motherboard tray, plus some thoughtful touches. Fractal includes three Velcro straps in the R5, which are used to route the front-panel cables by default. The Define R5 also has plentiful slots for zip ties in this area, if the Velcro straps aren't enough. The three fan headers and SATA power connector for the built-in fan controller reside here, as well, along with two 2.5" drive trays.
The metal drive trays at the front of the R5 can accept up to eight 2.5" or 3.5" drives. These trays feel sturdy, and they slide in and out easily. Still, the R5's drive mounting scheme is my biggest complaint about the case. Mounting a drive to a tray requires four rubber grommets and screws, unlike the simpler snap-on plastic drive trays in almost every other modern case. What's more, this mounting system means that owners will have to worry about keeping the Define R5's included hardware organized and stored somewhere. Good luck.
The Define R5 makes up for its somewhat fiddly drive mounting system with its incredible modularity. Every drive cage in the case is removable.
While the drive cages are ostensibly tool-free, the thumbscrews used to secure them are super-tight out of the box, so a screwdriver is a must here, too. With all of the drive cages removed, the R5 can accept radiators up to 360 mm in length behind the front fan mounts, as well as extra fans or radiators at the bottom of the case. The Define R5's instruction manual suggests that the bottom drive cage can be moved to the middle of the case, which is nice if you need both front radiator support and room for 3.5" drives. For a full accounting of the various drive cage configurations that are possible with this case, check out the Define R5's manual.
Another nifty modular feature is the trio of "ModuVent" covers at the top of the case. These foam-backed plastic panels can pop out if you want to mount fans or a radiator to the R5's ceiling, or they can be left in place for maximum silencing power.
The panels are a neat idea, but I wish Fractal had made their retaining clips more finger-friendly. As it stands, these clips are tiny and difficult to manipulate. It also would have been really slick if Fractal had included a matching magnetic filter for each ModuVent panel, since the top vent is unfiltered when these panels are removed. Corsair includes a magnetic top filter for the Obsidian 450D in the box, so such an add-in wouldn't be unprecedented.
The omission of a top filter is also strange considering Fractal includes a full-length filter at the bottom of the case. While some builders might put a fan or radiator down here, I think top-mounted fans or radiators are a far more common choice. For those who do wish to add bottom-mounted cooling, removing the drive cages makes room for a pair of 120- or 140-mm fans—or a radiator up to 240 mm in length. Installing fans or radiators here will limit the length of the PSU you can install, however.
The R5's PSU emplacement is similar to that of other cases I've tested recently, which is a good thing. The power supply rests on four wide, rubber feet to prevent vibration from traveling into other parts of the R5's frame.
With the 5.25" bays removed, one can mount three 120- or 140-mm fans, or radiators up to 420 mm in length, at the top of the R5. Some radiator sizes are subject to a 55-mm height limit here, however, so be sure to check the manual for compatibility.
The side panels of the R5 are both lined with the same dense foam that we saw behind the front door. Non-windowed R5s have another ModuVent cover on the side panel, and that cover can be removed to make way for another 120- or 140-mm spinner. The windowed R5 gives up that fan mount for its transparency, however.
Overall, the Define R5's interior is spacious and well-designed at first glance. Next, I'm going to install my Casewarmer system, along with some air and water coolers.