both side panels can be swung open thanks to an elaborate hinge system. These hinges also allow you to disconnect the side panels from the case without the need of any tools, so that you have clear access to the interior from all major sides.
The orange tabs hold the central spine in a specific position, which is also clearly marked with numbers between 1 and 7. The orange pieces are only needed during transport, but if you don't plan to move anything around, you could just leave them in place as well. By allowing the spine to move, using the corresponding numbers to align with the instructions in the manual, it gives you the flexibility to go from a 77 mm high CPU cooler in combination with a GPU of up to 43 mm thickness to a mere 48 mm CPU cooler and space for an up to 73 mm thick GPU (62 mm, if the GPU is taller than 145 mm). While this may sound complicated, having these numbers is crucial and very welcome, as you can plan your components in advance to ensure that everything will fit within the Fractal Design Terra. The number system to secure the spine also take any guesswork out of this - all an excellent way to communicate this flexibility with the user while building the system.
On the inside, while there may be a lot going on with the pre-installed PCIe 4.0 riser cable and the IO/power cords, the Fractal Design Terra follows the classic layout of CPU/motherboard + PSU on one side and dedicated room for a GPU on the other - with the option of liquid cooling. As mentioned before, there are clearly two 120 mm cutouts on the floor, but Fractal only communicates the one towards the front of the chassis as a position to potentially install a 120 mm fan.
Towards the front, on the GPU side, there is another possibility to install a 120 mm AIO unit. There are two cutouts here, so you have a little flexibility on which position to pick from, but Fractal also mentions doing so will lock you from installing an SSD or fans on the floor of the Terra, as that is where the tubing will be routed instead. In that picture it is also worth nothing the detail to engineering with a rounded bend that straightens out to the left of this area with the aim to make the absolute most of the space by giving the PSU side a few more millimeters of room. In addition to this, the steel used is thick and hefty.
The PSU section allows for an SFX or SFX-L unit to be installed. While the standard orientation is with the fan facing the outside of the chassis, Fractal also suggests that one could install it facing inward instead to create some additional airflow within. Fractal has pre-routed the power cable so that you just have to pull it up and plug it in While the on/off switch of the unit will be inside the case, you will easily be able to reach it by pulling off the exterior case cover at any time. The motherboard tray towards the back of the case is meant to hold the board upside down, so that the PCIe slot is at the top edge. This means that some of the cable routing isn't straight forward, which is why Fractal also has several suggestions explicitly mentioned in the manual.
To install your GPU, you may remove the whole contraption containing the riser cable as well as expansion slot bracket. This allows for easy prep of the unit outside the confines of the case, while also helping in trialing where and how to route any cables. Even though the bracket is geared towards dual-slot cards, you should have no issue with thicker variants as long as they generally fit within the Fractal Design Terra dimensional limitations.
In terms of storage, the Terra can hold up to two 2.5" drives. One would be embedded in the well engineered front panel and held in place by two branded Velcro strips. The other utilizes the provided HDD tray to snap onto the floor of the case instead of a bottom fan.
In terms of cables, besides the power cable, you will find a USB 3.0 as well as USB-C wire. While the former is flat, the latter is of the rounded kind. And, as the Terra has no reset button or any status LEDs, all that remains is a single connector for the power button.