Solid advice by Falcorambone . If you do take your CPU block off , make sure you clean the waterblock as well as your CPU and reapply a fresh , uniform , coat of thermal paste . The best spot for your drain port is the lowest point in your loop AFTER the pump this is so that you limit the chance of your pump running dry , which will damage it very quickly . Since you have a pumpres combo the most logical spot is right at the out port of your res as stated by falcoram . You can use your own judgement , but from the pic it looks like either a Y or a T splitter will work . When you do add the splitter , do consider adding a drain v a l v e V alveBlackHandleSparkledpB 007 N 8 SE 3 Crefsr 128 ? mA 3 GO 5 VFCNOM 5 I 7 spcieUTF 8 qidtelsr 128 k e y w ordsbitspowerrefinementsp 6 % 3 AA 3 GO 5 VFCNOM 5 I 7 . You can connect it directly to your splitter with a male to male adapter , however , in my experience , adding tubing that comes off the splitter to your drain portvalve gives much appreciated flexibility when you do drain your loop . One last thing you don ' t have to worry about draining your entire loop . Your radiator is most likely going to remain full , which is totally fine . If you run into issues where you cant get some liquid out of a tube , turn your pump off and let it settle before turning back on as well .