EDIT: For completed loop, skip right to post #36 I'm going to start by saying that all I did was a dinky CPU loop, nothing too impressive so don't get your hopes up. However if you're curious to know what building a custom loop is like for a first time watercooling noob and care for my <del>ramblings</del> thoughts, read on. Since the entire thing is far too tl;dr to fit into one post, I'm going to break it up into several posts to make it easier to manage, and also so those of you who just want PICS NAO can skip right ahead to the last post and ignore everything else. Quick background: desktop in sig finished around end of September. Here I have some pics of the finished build. The Enthoo Primo is an extremely watercooling friendly case, and it just didn't feel right to have a Corsair H110 CLC as the only "watercooling" component. Plus I was drooling at the aesthetics of the many watercooling builds, and it just seemed like a great way to kill some time and tinker with stuff, which I enjoy more than using the computer sometimes. After spending god knows how many hours researching online, picking out all the technical drawings and doing a "mockup" with cardboard and measuring tape, I finally took the plunge over the Black Friday weekend. First I had to gather all the necessary materials: < Parts List Alphacool Nexxos XT45 420mm radiator Koolance COV-RP450 D5 pump/reservoir combo top + BDY-TK80/120 tube res Koolance 380i CPU block Koolance QD4 quick disconnects Primochill Advanced LRT 3/8ID 5/8OD tubing Swiftech MCP655 variable-speed pump (rebranded Laing D5 vario) Deionized water and a secret ingredient which I will touch upon from Sigma-Aldrich (perks of being a chemist ) and god knows how many Bitspower fittings If you care about why I picked these components check the spoiler. (tl;dr warning) Spoiler For my loop I decided to go the "max flow, lowest restriction" route, especially since I'll be using quite a few pairs of quick disconnects, which can add significant flow restriction if you pick the wrong kind. The XT45 is an excellent all round radiator with very low restriction that has superb performance regardless of fan speed. The Koolance 380i block might not be the lowest restriction, but offers great performance and is fairly consistent from one mount to another. As for the pump, seems like Laing is the only player these days, with Eheim and Iwaki becoming increasingly rare. The choice was pretty much between the DDC and D5, and it was easy. A picture is worth 1000 words. As for why I went for Swiftech, wanted a D5 without a tach sensor. When deciding between a bay or tube res, it seemed that bay res in general are harder to fill and drain, and have a harder time with bleeding the loop, so I stuck with tube. Then came the question of whether to keep separate pump and reservoir mounts or use a pump+res combo. Ultimately decided to go the combo route since it made loop planning much easier, plus none of the 3 pump mounting points in the Enthoo Primo case were ideal for my setup. The Koolance D5 pump top (COV-RP450) comes with a pump body cover, and offers very good performance for the money, so another easy choice. Primochill's Advanced LRT tubing contains no plasticizers. You don't want plasticizers. And to wrap it up, Bitswpoer has become the time-proven gold standard when it comes to fittings. They do come with a matching price tag, but dammit if I'm doing a custom loop I'm doing it right. Besdies no point trying to save $100 on fittings only for them to leak and ruin a $3500 computer. And with that let's carry on... Before I could install however, I had to fix a problem: You see the case PCI bracket plate is riveted to the rear case plate, and it is just a hair too wide for the Koolance bracket so the screw holes don't align. Had to grind about 1mm off the Koolance bracket to make sure the M5 screws I bought would thread through.