Cooler Master designed the HAF XB case to accommodate almost any sized board, ranging from the micro-ITX to the overly large E-ATX sized motherboards. Because of the case's removable motherboard tray and layer separation between the motherboard and drives/PSU, space is never an issue.
The case easily accommodates the larger size of an E-ATX board, as illustrated with the GIGABYTE Z77X-UP7. The board easily fits on the removable motherboard tray with some room to spare along all sides of the tray. Because of the room provided in the front of the case, you should have no issues with a front mounted radiator using a larger board. The better news is that a standard-sized ATX form factor board would take up even less room.
Using a micro-ITX board, the motherboard tray and top portion of the case look monstrous. The board is so small in comparison to the tray that you could route cables through the front edge of CPU cut-out in the tray itself.
From a back view of the case, you can easily see how the PSU mounts and sits in the mounting mechanism. The PSU mounts to the back plate using four screws. The mount itself extends out from the case's back plate by about an inch. No worries though, the PSU is firmly mounted and secured in place and the back mounting bracket blends in well with the back of the case.
With a Corsair HX750 PSU mounted in the case, you can see that things start to get a bit tight between the PSU and the hot swap bay PCB, especially when using a modular PSU. There remains two to three inches of space between the them, but that quickly gets used up when you start plugging in cables to the modular PSU and into the hot swap PCB. If you choose to use an overly large PSU with this case, you may have to remove the hot swap bay PCB entirely so that you have adequate clearance for the PSU cables. In any case, make sure to detach the PSU mounting bracket from the case (keeping the PSU installed in it) and slide the PSU out of the case a few inches to give you more room to work with the hot swap PCB.
The hot swap drive trays easy accommodate both 2.5" and 3.5" form factor hard drives. A 3.5" drive sits snuggly in the tray, while a 2.5" SSD is almost lost in all the remaining space. Notice how both devices sit in the tray so the the data and power connections correctly mate to the hot swap bay PCB ports.
For using 2.5" drives in the internal drive cage in the back lower left corner of the case, drive rails must be affixed to the drive prior to insertion. The drive rails are tool less and simply affix on to the sides of the drive. The drive is held firmly in place by the rails, which snap into the outer edge of the drive cage. Drives can be removed by pressing the drive rail tabs inward towards each other and sliding the drive out.