Before we dive into the interior, it is noteworthy that the metal panel has individual, custom shaped, white & magnetic dust filters on all openings. This is an area that you will not see, but ASUS has gone the extra mile to make them white nonetheless. And, even though traditional square ones would have worked too, they took the time to make them fit perfectly. Also worth mentioning is the fact that you may pull off the front glass if need be, but for our build we did not have to resort to that.
On the interior, the general layout of the ASUS TUF Gaming GT502 is essentially the same as all other sandwich ATX enclosures, but as always, the details are what makes it stand apart. On the floor of the case, there is a multi-functional frame that may be removed and filled outside of the chassis. It may hold three 120 mm fans or act as a mounting frame for the three hard drive plates that ship attached to the side of the chassis by default.
Those plates are all branded with TUF Gaming and provide you with the utmost flexibility between your fan/cooling setup and the drive configuration. Out-of-the box, these are placed on the side mounting where three 120 mm fans or a radiator of up to 360 mm could go instead. ASUS went as far as to cover the I/O PCB to hide it from view and not disturb the interior cleanliness of the GT502.
In the rear of the main compartment, there are the eight expansion slots. The vertical plate is meant to replace slots 2 to 7, leaving you with the top most and bottom most horizontal ones. Both of those are usually not useful to modern ATX boards, but that just means you have additional room below the motherboard for cooling even when going vertical. Above that is the aforementioned 120 mm fan mounting position with enough room above it to comfortably fit fans or AIOs in the ceiling.
ASUS has opted to put a bit of its own spin on the layout behind the motherboard tray. While most brands put a HDD cage above the PSU bay, ASUS has moved it to the bottom front instead. The freed space is instead used by yet another fan/AIO/HDD mounting bracket. This means you could install an AIO and run the tubes through the opening at the very front of the case, to the left of the HDD plates. As such, even with such a configuration, you won't have to sacrifice the looks or expandability of the side mounting possibilities. In total the ASUS TUF Gaming GT502 can hold up to 13 case fans and still retain a single storage bay.
In the bottom of this compartment, the PSU bay utilizes a metal support bracket with two cable routing holes left and right of it. Unfortunately, ASUS has not placed any grommets here even though that would have been quite useful. A foam pad on the back of the motherboard tray ensures that the PSU sits snug and vibrations aren't amplified by the chassis itself. In the front, there is a single HDD cage which may hold a 3.5" or 2.5" drive. One could argue that ASUS could have designed it to be able to hold one of each instead for even more storage. There is space between this tray and the mounting plate, but it is not enough to accommodate a 3.5" drive and the cage at the same time.
Looking at the ceiling, you can clearly see the mounting frame and how it could be flipped over to be hanging down the ceiling instead of facing upward. In the default configuration there is already plenty of room for classic AIOs, with a max of 73 mm in clearance being communicated by ASUS. This is plenty for the usual 52 mm of most such liquid cooling setups, but just shy of the 77 mm needed to allow for push/pull assemblies.
In case it wasn't apparent yet to what lengths ASUS has gone to keep white truly white, look no further than the cable leads. All of them down to the ARGB wire for the front log and the front panel plug are actually white. ASUS even went as far as to wrap the exposed end of the audio cable in white tape! All of the connectors are of the usual shape with the USB 3.0 one being flat for added flexibility. ASUS also employs a unified motherboard front panel connector to make this step of the assembly a breeze.