Stackable cases seem to be Thermaltake's new thing. Barely two months after releasing the Core V21, the company has added three more stackable options to the Core series: the Core X1, Core X2, and Core X9.
All three enclosures are (roughly) cube-shaped, and each model can be stacked vertically atop another one of the same type. In a stacked config, one enclosure can house the system's vital components, while the other can be dedicated to heavy-duty liquid cooling setups and large storage arrays. The new Core offerings each feature a dual-chamber design, as well, with one chamber meant to accommodate the PSU and modular drive bays. Also, these cases each have a swappable windowed side-panel, which can go on either the left or the right side. The front-panel I/O, which sits on the left side of the bezel and includes up to four USB 3.0 ports, can be similarly relocated, too.
Those are the similarities. Now, for the differences.
The Core X1 is designed for Mini-ITX motherboards, and it's the most affordable of the bunch, at $99.99. Its relatively ample dimensions (16.8" x 11" x 18.5") leave room for up to six storage devices, 7.9" tower-style CPU coolers, 15.7" graphics cards, and PSUs up to 8.7" long. You can even fit a 360-mm radiator at the top. Thermaltake ships the Core X1 with two pre-installed 120-mm fans—one front intake and one rear exhaust—which ought to keep any Mini-ITX config nice and chilly.
The Core X2 is a little pricier, at $129.99, but it's able to house larger microATX motherboards and up to 10 storage drives. While the default cooling setup is the same, there's room for radiators in the bottom and side panels. The X2 can also take taller CPU coolers up to 9".
Topping the lineup, the Core X9 carries a $169.99 price tag and has enough space for full-fledged ATX motherboards as well as a maximum of 12 storage devices. It ships with a 200-mm intake fan and supports 480-mm radiators on its top, bottom, and side panels. You can see a full spec sheet for this bad boy, along with the Core X1 and X2, at the bottom of this page.