I still say the fanless Kingwin 500 will stand up to the load better than a 400 while keeping inside it's temp range. Heck, mount a fan to the outside of the fanless unit if need be, powered by your Rheobus and able to be turned off when need be. Warranty in tact and tailored to your needs.
Fanless units have their sinks connected to an external sink that's part of the shell, stick on a thermometer to track it's temp if you wish to see...then there's no alarm to interrupt your recording.
**BTW, you've said you can't move the PC out of the room, but can you move watercooling outside of the room? It's no big deal to stick a sink on the power supply as well as the CPU & GPU and let the water move the heat elsewhere that fan and pump noise is fine.
Just another thought. My water cooler is external, and it would be cake to add 30 more feet of tubing. You can even hang it on a wall..