A Closer Look - Inside
To access the insides, simply detach the thumb screws and pull the side panels off the chassis. Both the front and top panels can also easily be pulled off. In the front is an opening for you to slide a GPU in, so you may take advantage of the full length of the case when picking the graphics card of your choice.
On the motherboard side is the pre-routed PCIe x16 4.0 cable on the bottom, which means the board will be right-side up. Towards the front on the same side of the A4-H2O is the PSU cage, which may hold either an SFX or SFX-L unit with its fan facing outward.
The GPU bay with its triple-slot layout should be able to hold pretty much anything you can throw at it thanks to the maximum 322 mm length. As it is installed upside down, there is also plenty of space for the graphics card to be fairly tall. On the floor, towards the front of the chassis, is that one 2.5" placement opportunity. As this is the only one besides what your motherboard provides in M.2 slots, odds are users will use it for their more affordable mass-storage requirements.
As the PSU is meant to be embedded inside the case, there is a cable running to the back of the chassis, so you may easily connect your external power cable.
All the cables are sleeved black and standard-fare. The internal power plug is also black on the outside, but sports a white insert.