I'm gonna kick things up a notch with this ravaged barbaric atrocity, with a 360 AIO strapped to a rectangular hole cut out using metal scissors on a rack mount case;
(Side-view)
This creature isn't as sexy as I envisioned it to be, yet pretty competent at running an overclocked CPU and a mildly overclocked GPU. All else is standard. The case and all modifications to make this "thing" a rack mount unit cost me somewhat in the neighborhood of 20-ish USD (including case, rails, fans, mounting brackets, tools, etc.). Props to our local "Craigslist" alternative!
(Component layout)
The specs are as follows:
CPU: i5-7600K OC'd @ 4.5GHz
Mobo: ASUS Z270-P PRIME
GPU: NVIDIA GTX 780Ti
RAM: Mixed kits of Corsair Vengeance LPX & Crucial BallistiX, 32GB DDR4-2400
Storage: 1*Samsung PM981 NVMe (512GB), 1*SanDisk X300 SATAIII (128GB), 1*Crucial M500 SATAIII (480GB), 1*Seagate Desktop SSHD SATAIII (1000GB)
AIO: GamerStorm MasterLiquid 360 RGB
PSU: Corsair CX750M
PCIe Add-ons: 1*Mellanox ConnectX-3 Single-Port 10GbE SFP Adapter, 1*ORIENT 6-port USB3.0 Controller (for UASP support)
In retrospect, I might have done a few things differently regarding radiator mounting, such as cutting off a wholly different part of the case or going with a smaller AIO for such a setup. Getting idle temps in the neighborhood of 25-30degC, with 60-70degC at full load, which is pretty nice compared to previous thermal throttling in 7 minutes.
(How it fits)
Now the reason I ended up in such a problematic situation was a sudden relocation to an apartment complex where every square inch of your living space matters. I managed to salvage a 16U server rack to rebuild my NAS, firewall and my own PC, as well as local switch (also rack mounted) and a HomeAssistant RPi all in one place. I had a go at creating a custom ventilation system for this (by carving out multiple 120mm circles in the rack's solid back wall and two 200m on the sides for intake), which worked out great (running off a Sonoff RF wired up with a temp.sensor, directed to activate upon hitting 45degC ambient). It all runs quietly (sits under the table not further away than 3m from my bed).
I might add a few dust filters extremely soon, because all the negative pressure is driving every single dust particle onto the mobo, and it's getting pretty annoying. The 60mm Arctic F6 PWM PST fan isn't that great at evening out the pressure of a blower-style graphics card cooler, an AIO and a PSU fan. And, unfortunately, of course I know about the back side being exhaust, therefore my setup draws heated air from other servers inside to compensate for the pressure. But I think I'm scrubbing the ceiling at how far I can push my current hardware without additional buy-ins, and therefore the complete reorganization is six foot under on my list.