Concept Sub-15 liter liquid cooled mATX dual GPU sanity checking

vluft

programmer-at-arms
Original poster
Silver Supporter
Jun 19, 2016
156
132
I recently got around to upgrading my workstation, but the case I'm putting it in initially is absolutely massive; a whole 25 liters. Obviously this won't do, so I noodled around with some ideas and roughly blocked out something that I think might work – I would like to run this by some of the folks here for sanity checking before I put a lot of effort into modeling, though, so here's my relevant hardware and a mockup of what I'm thinking.

  • ASrock X399m w/2950X
  • Vega 56 ("primary" card, because AMD has better Linux drivers these days; rarely if ever going to be run at full power)
  • 1080 TI, FE (for PCI passthrough for Windows VM; notably, output ports of this card do not need to be accessible as I'll be using KVM frame relay for it)
  • NVMe drives for all storage
Goals: not the smallest thing in the world, likely, but minimal wasted space and full watercooling. Theoretically it needs to be able to sink 600W but in practical use the heaviest loads it'll be getting is around 450W, as I'm never gonna drive both cards at full tilt simultaneously.

So here's a (basic blocked out) mockup:



Legend:
  • Grey (in the back): mobo, blocked out to include io plate, so most of that is empty space
  • Green: 1080ti, in an EKWB single slot waterblock
  • Red: Vega 56, in ditto (both cards are blocked out to include the terminals and a little extra space on all dimensions so it's not quite as tight as they look there
  • Black: Radiator, Alphacool crossflow 80mm×60mm quad
  • Brown: Fans (probably Noctua NF-A8, but there might be something better)
  • Yellow: 2x HDPLEX 400W AC/DC
  • Pink: HDPLEX 800W DC-ATX
  • Blue: DDC pump with top
Mobo & video card IO exits downward into the empty space there, which on actual case would be open at the back (back being the non-radiator fan side) and bottom with cables being routed out an open hole at the back. Video cards are using flexible pcie risers and are mounted to the side of the case. Rear fans are inflow, front fans are push through the radiator. No case vents except where the fan&radiator inlets/outlets are. Plug for the power supplies is TBD but probably above them facing inwards. On the CPU I'm gonna use a Bitspower or EKWB monoblock for this board so I get cooling on the VRM as well, and I figure the general windtunnelness of the case is gonna be sufficient for other passive components. Planned cooling flow is to go from least to most TDP, so pump -> CPU -> Vega -> 1080 TI -> rad -> (res?). As blocked out here internal dimensions are 14.2 liters (390mm×428mm×85mm) but I expect slight growth before I'm done.

Concerns:
  • Is that gonna be enough sink for that amount of power without fans being very loud? My gut feeling is that it will be as the rad total volume is a bit higher than e.g. a 120mm×50mm triple, but I'm unsure if airflow will be okay on 80mm without super high RPMs. I'm not a watercooling expert of any stripe, though.
  • How much of a PITA is this loop gonna be without a reservoir? I can probably fit something res-like in the front between the radiator and the DC-ATX
  • Is it gonna be a heat dissipation problem if the AC/DCs are adjacent? I think probably not as theoretically they should be fully passive at less than 250W each which I should nearly always be under, and the fans are there if it's too much.
Is there anything else real dumb I'm just missing? I think it shouldn't be the world's toughest case to make if I can get it on account of just being a box; I expect it'll be a royal pain to plumb but that's nothing new.
 
Last edited:

darbie

Efficiency Noob
Feb 18, 2019
7
2
I've been doing a similar project, except that I've given up on the idea of water-cooling. I've been able to find pre-made sketchup models on the internet which has made screwing around with different layouts and positions easier. With the graphic that you have produced, it is difficult at a glance to get an idea of air-flow, which seems to be the achilees heal for most SFF cases I see.
 

vluft

programmer-at-arms
Original poster
Silver Supporter
Jun 19, 2016
156
132
Here's a top view of that mockup:



Shaded area on the mobo block there is mostly empty space, and all airflow is from left to right through that area.