Right, from the get go this is more "because I can" type of project and most WC parts I already have in some form or another. So currently I have 3(4) systems in the rack: 1. x2700x + gtx1070 under water atm, acts as main PC, cpu/mb will be moved to second NAS then zen3 is out and become system 4. 2. x5650 as VM server, currently stock cooler, but will be going under water no matter what 3. Phenom II x6 NAS, under air Plan is to leave system 1. in its own loop (single 360 rad), but do a shared loop for the rest, single 360 rad at the start, expanding as needed. Potentially watercooling 2700VA UPS and switch at some point. Rads go at the back of the cabinet. Shared loop will have flow/temp sensors for monitoring and emergency auto shutdown in case of a pump failure. For the plumbing: * 15mm copper pipes on the side of the cabinet for water distribution, soldered standard brass fittings, hoses with QD to the systems chassis. * Single reservoir at the top * Single Eheim Universal 230V pump at the bottom Now the question is - should I put systems in parallel or in series (with bypass valves)? Parallel might result in lower temperatures for individual systems, but will make managing waterflow through different waterblocks more difficult. Any suggestions/insights or just telling me how stupid I am for just thinking about doing this are appreciated.