got one 280mm AIO in today - time for an test build in my prototype...
first step: install the motherboard standoffs, GPU bracket, power button, top exhaust fan and four of the side panels as shown below
depending on the mounting mechanism of your AIO it might be a good idea to install everything on your motherboard before mounting it into the case
after the AIO is mounted, time to put the motherboard in the case and fix the GPU
next step: install the rear side panel with the PSU attached and do some cable management to prevent cables / tubes touching the fans. I am going for an all exhaust fan config, so the fan from the PSU should face inside. If you go for all intake, you can flip the PSU.
fix the rad to the left side panel and attach the last side corner profile to the panel
now you can close the case by sliding the panel into the corner profile slots
despite the pretty large clearance I made below the I/O, some connectors (e.g. Display Port) will not fit. So considering that you have to use slim/angled adapters anyways, I will decrease the I/O clearance to support up to 340mm long GPUs instead. Also @Nero
had a good idea to make some threads at the bottom, so you could add some HiFi feet.
build complete... well... almost... I forgot the SSD!
luckily you can take off almost all the side panels - without taking apart the whole thing - so I could just connect it from the top of the case...