ThrashZone, that's an interesting idea. I hadn't considered it up to this point, but I would certainly be willing to entertain that in the event that the current configuration struggles.
The biggest issue I might have is sheer space requirements. I'm already going with a large, double-width case (a Thermaltake WP-200, because CaseLabs shut down just before I tried to place my order) and I literally don't have any room to spare. However, at this point in time the rough layout of the WP200 is intended to be:-
1. Windowed Side:
Motherboard and mobo related components
AquaComputer Aquero [front mounted]
Media Card Reader [front mounted]
1 x EKWB CE560 Radiator [roof mounted, servicing the CPU]
2. Non-Windowed Side:-
3 x Pump/Adapter/Reservoir Combos
2 x EKWB CE560 Radiators [1 x roof mounted, 1 x side mounted, servicing the "upper" of 2 2080Ti GPUs connected via nvLink]
2 x Optical Drives
2 x EKWB CE560 Radiators [side mounted, servicing the "lower" of 2 2080Ti GPUs]
There is a [narrow] chance that I might come across a chiller unit small enough to fit inside the "non-windowed" side of the case. I can easily make up mounting/fixing brackets and I can use one of the unused PSU cover plates to surface-mount an IEC power adapter that allows me to plug an external power lead in to the rear and run and internal mains cable to the unit for power. As long as I can find a way to safely exhaust the heat I should be able to make that work...
On the other hand... I currently have a 6-Core i7 4960XE overclocked from stock 3.6GHz to 4.4GHz running in to a dedicated EKWB 240 radiator and which under high load gives me max temperatures at 44-45 centigrade. If I can stick to something like that, I'll be happy.
The rest is a bit long-winded, but:-
Going from a 2x120mm-fan radiator to a 4x140mm-fan radiator dedicated to the CPU should give me some headroom... Now, I appreciate that TDP indicators go out the window the moment we overclock, but the TDP for my 4960XE is quoted as 130 watts and the 7920XE is listed as 140 watts...
Not being remotely clever, I just use simple math:-
130 watts in to 2 x 120mm fans = 65 watts heat cooling per fan... yielding 44-45 centigrade under load. This in a room which is typically in the range 22-24 ambient, so 20-23 centigrade above ambient - under load.
140 watts in to 4 x 140mm fans = 35 watts heat cooling per fan... yielding TBD centigrade under load. And in theory I should get considerably more cooling from the larger fans, since the area covered by a 140mm fan is roughly 136% of that covered by a 120mm fan...
Similarly, the 2080Ti's are rated at 250 Watts TDP each:-
250 Watts in to 8 x 140mm fans = 31.25 watts heat cooling per fan [each 2080Ti is getting a pair of CE560 radiators, in series].
5 radiators = 20 primary cooling fans. I bought Noctua NF-P14S Redux 120 Fans, rated at 19.6 dbA at 1200rpm... but of course I'm configuring them in to 5 fan channels using the AquaComputer Aquero Fan Controller. Each radiator will have an in-line temperature sensor on the output port and I can use the temperatures each sensor reads as input to set fan speeds via curves configured in the Aquero.
Currently, my concerns are:-
1. Can the Aquero help me keep fan noise down, given that I'm going from 5 120mm fans in my current machine to 20 140mm fans in the new one?
2. With a steel case, 5 radiators, 3 cooling circuits and sundry odds, can I keep the weight of this monster down so that I can still move the thing?
Time will tell...