There isn't anything too surprising about the internal layout of the Osiris, but we did see why the side cover was giving us problems.
Due to someone treating our test unit like a soccer ball (and they must've been really rough because, the packaging foam was quite thick and sturdy), one of the braces for the rear spring-loaded hinge broke, allowing the hinge fall off its mount. These spring hinges are actually one of the nicer systems I've seen for holding and guiding side panels into place. Sometimes it's amazing to me just how hard it is to get a side panel perfectly positioned for it to lock, but with the Osiris you just gently guide the panel downward at an angle, and then use the latches at top to secure it. Nice.
The inside of the Osiris is rather spacious, with no dividers or crossbeams restricting access to the internals or interfering with irregularly-shaped components. One has to wonder if some additional bracing might have helped the case from getting knocked out of square, but the ability to withstand rough play really shouldn't have to be a consideration when buying an enclosure. We're confident that the Osiris is strong enough to endure typical PC settings, and we'd rather have easy access to its guts than superfluous dividers.
Drive capacity is in line with expectations for a case this size, with the Osiris capable of housing four hard drives in a fan-equipped cage and five 5.25" drives that line up with the pop-out panels up front. Interestingly, the Osiris completely lacks an external bay for a 3.5" drive by default, but there is an adapter cage which will fill the 5.25" pop-outs if you want to run a floppy drive, or more likely, one of those everything-in-one flash card readers.
We're pleased to see some basic vibration absorbing material for each and every drive, including the externally-mounted 3.5" drive. In practice, however, these small strips of rubber haven't wowed us with their noise reduction performance. Notice that Hiper has designed extra fins of aluminum onto the side of each drive slot, presumably in an attempt to keep the drives running cool.
Instead of sliding drives in from the back or the front, Hiper takes a different approach. To install drives, first you must remove the entire front panel from the case. This is a relatively simple "pull hard enough until it gives" procedure, but I would have preferred if a latching mechanism similar to the side panels were implemented instead. Note the 3.5" adapter plate I mentioned before; it can be moved into one of the top five slots and mounts flush with the rest of the bezel.
Even the hard drive cage is designed to slide out of the front of the case rather than being removed internally, which makes for a bit of a pain if all you want to do is change a hard drive. The drive rack does have mounting slots that allow for a large range of motion for all the drives, allowing one to line them up with the front bezel or push them slightly forward or back. It doesn't hurt that Hiper includes enough thumbscrews for a tool-less installion with any drive combination you could imagine, but more on that later.
The only thing really worth talking about in the motherboard area is the excellent cooling potential around the CPU area thanks to dual 120mm exhaust fans. As the ever-popular Antec P180's design has shown, it's generally better to exhaust all the hottest air from the top rear of a case instead of limiting airflow in the region with another heat-producing component, like a power supply. It's also easy to see in these two shots how the power supply's cables aren't going to be obstructed by any kind of compartmental barrier, which will make for an easier install.
Every power supply I've ever seen should fit in the Osiris. Unlike some cases, there are no obstructions whatsoever on the bottom plate. The only thing to make sure of is that the PSU's fan is positioned over the supplied fan filter. Then again, doing so is only necessary if you want your PSU getting its air from outside the case—the Osiris' power supply mounting plate has screw holes for an inverted install, too.