The Phantom 820 is plenty roomy, supporting XL-ATX and Extended ATX motherboards. As we've pointed out, the case's built-in cable management is a high point as well. Because it offers so much space, motherboard installation is really pretty easy.
Although we really like the fact that NZXT exposes two USB 3.0 and four USB 2.0 ports on the top of its case, those second-gen connectors have to be fed through a pair of USB 2.0 headers. Now, we're not sure how many modern motherboards include more than two of those headers, but if yours isn't one of them, you're going to have a hard time hooking up four USB 2.0 ports and the Phantom 820's built-in card reader. In our case, we used an adapter purchased separately to re-purpose a USB 3.0 header.
There are four openings for water cooling next to the expansion slots, and you'll find enough space under the Phantom's top panel for a 240 or 360 mm-long radiator. It can't be more than 60 mm thick, though. And even then, some parts of the top 5.25” drive bay need to be taken off first.
Frankly, most users don't need high-end water cooling systems with separate loops for the CPU and GPU. It's good to know that if you're one of the ones who can put such an intricate circuit to use, however, this case supports it.
NZXT's Phantom 820 is one of the few cases that provides a perfect fit for the ATX back plate. Some enclosures are less than precise with this one point, and it's nice to have the I/O panel snap into place securely.
Look how roomy this thing is. Connecting cables is a piece of cake. You don't have to bend your hands or risk slicing your fingers on an unfinished edge. Holes in the motherboard tray are neatly covered in grommets so you don't see anything underneath. And plenty of room for larger platforms means the Phantom 820 could conceivably support four dual-slot graphics cards, though we'd probably recommend a couple of GeForce GTX 690s, if you really wanted to go that route.