a few years ago i built a massive external watercooler to try and achieve a very quiet 3d workstation.
consists of a pair of mora3 radiators in parallel, a reservoir, and a pair of d5 pumps in series. fans are 6x silverstone 180mm. all internal tubing and interconnects are 1/2 inch.
this setup is connected to my workstation via a 3/8" umbilical 3m long with quick disconnects on the end.
the workstation has a 3930k and 2x titan x all in series, on a 3/8" set of fittings and tubes.
the reason for the fatter tubes in the cooler and the thinner umbilical and workstation fittings are:
the cooler is future proofed and was designed to cool whatever hardware i could throw at it, now and future.
the umbilical and pc use 3/8" due to flexibility of umbilical and space in workstation.
it has been working beautifully for years..
even with both gpus and the cpu (at 4.6 ghz) rendering flat out together, the gpus stay around 33 degrees and the cpu sits at around 46 degrees.
this is with cooler fans running at just above stall speed, and the twin pumps both on setting 1 of 5
now its time to get a new beastly workstation.
ideally i wish to continue cooling the old one, as its still useful for rendering.
new workstation will probably be
threadripper 3 (64 core if possible, will find out soon enough
4x Titan RTX gpu, or Ampere gpu of similar spec if available (my job involves tons of gpu rendering. the extra gpu ram is very useful)
i would also like to cool vrms on mobo.
i dont plan on doing too much oc on new workstation.. maybe some mild stuff.
so, my external cooler will be getting put to the test. i guess ill need to crank up the pumps!
my current plan is to either just run a massive serial loop, with (in total) 6x gpus and 2x cpus and vrm cooler all in series with dual pumps, and only the radiators in parallel ( iirc, this was on advice of manufacturer who showed marginally improved performance with slow flow rate in those rads.)
or, run the two workstations in parallel with each other, and use a valve to balance flowrate. in that case it would be 2x gpu and 1x cpu on one side, and 4x gpu, 1xcpu and 1xvrm cooler on the other.
the second option makes a touch more sense, since the 1/2" tubing in the cooler might match quite well with a pair of 3/8" loops.