To access to the interior, simply pull each panel off. While the external part of the frame is black, the internal pieces are actually white to match the exterior of the Zalman X3. On the shroud, you will find two 2.5" trays in black for added contrast. These are held in place by thumb screws. A large opening in the shroud towards the front is meant for a large radiator setup. An unsightly yellow sticker on the shroud warns users to use the right cable for Gigabyte ARGB connectivity. While I understand the precautionary side, this is a bit excessive as that same warning is found on the cable itself, which is where you really would want to be reminded of it anyways.
Turning the case over, there is actually surprisingly little to talk about. There is barely any space between the motherboard backplate and side panel, yet Zalman placed several cable hooks here. We will try to use some of these in our build to see how far we get with them. Two Velcro strips have been placed in the cable trench towards the front of the chassis. If you look closely, you can see the fan and ARGB controller behind that massive cable mess.
Underneath the shroud in the front is an HDD cage for a 3.5" drive within and your choice of a 2.5" or 3.5" variant on top of it. The space above the tray is used for the three fans and any potential liquid cooling you may opt to install. Zalman also includes a GPU support bracket, which is really nice to see. Unfortunately, it is made out of plastic, but it should still be able prop up a long graphics card.
The PSU bay underneath the shroud is pretty straightforward. You should be able to install all but the longest units. Above that are the aforementioned expansion slots with reusable covers. Zalman did not include thumb screws, which is unfortunate. The 120 mm fan in the very top takes up most of the space, but may be upgraded to a 140 mm unit if you like. Note that all four fans come with 3-pin headers and generic 5 V ARGB cables, so you may be completely brand agnostic when it comes to incorporating these into your build.
Taking a quick look at the ceiling, you can clearly see the offset mounting holes for 120 or 140 mm fans, with the PCB and connectors for the I/O towards the front of the Zalman X3.
All the cables within the X3 are of the default variety. Zalman allows you to control the ARGB elements with the motherboard as well, and here, you will also find that localized warning message for Gigabyte users. The controller board itself is powered via a SATA connector.