Tat thing has some beautiful engineering, but as Linus says, I'm really interested if a single (I would assume) 480 rad is enough to cool it all!
A 3x140 rad is slightly more fin area than a 4x120. A 120 for each GPU is more than sufficient for a rack case with shared airflow.
Volume wise it's fairly big, could house a more traditional setup easily. A lot of empty space in there.
It's also a shared rad. You'd need to be maxing out all 4 GPUs and the CPU all at the same time before you'd need to start worrying about thermal limiting.
In the kind of workloads that thing is designed for its far more likely though, as rendering and AI training will utilise as much as you can give it. And if you're not using it for those loads that system isn't for you.
I'm sure it'll be fine, I used to run with 4 290s 24/7 on a weaker WC setup, it ran warm, heated up the house but still better than on air. I shifted down to three in the end as I was at the limits on my PSU, even with 3 it would pull ~1.2Kw from the wall Can't remember CPU i ran then.
Remember, rack mount. This isn't a cooling system specced for 'let's overbuild it and then install fans that sedately rotate so as not to cause the barest mouse-whisper', it's going to be running high-RPM screamers next to a bank of other high-RPM screamers in a room with forced cooled airflow. This is not the Idyllic Realm of Noctua, this is the Harsh Dominion of EBM-Papst.
