@IIcx
Thanks for the detailed instructions on drilling holes for an external radiator. At the time when I was considering mounting it externally, I had considered this option but it was too daunting of a task and then I found out about these G1/4" PCI brackets (if only I had known...).

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In the end I didn't bother giving the clicking MCP355 another try and bought a brand new MCP35X, what a change! I leak tested the EK Supreme HF (re-assembled with the partially crushed o-ring) in a temporary test loop and 2 excellent news came out of it:
  • The EK Supreme HF doesn't leak anymore! Fortunately, the o-ring was still functional after re-mounting it, very carefully this time around. Had it not worked, I wonder if the o-ring of an old MCP355 would have fit? It's a lot thicker but seems to be about the same diameter.
  • The MCP35X was a very good surprise, it gave be a good feeling throughout: excellent build quality, the built-in top is super nice looking and sturdy, smooth operation even at the full 12V. With just the molex plugged-in (no PWM), so running at 100%, it's almost silent, despite all the air bubbles in the 10 minute run. Also, it starts up more gently than the MCP355: holding it in my hand I felt it gradually speeding up, from shaky in the first 0.5 seconds to full speed within a few seconds. The MCP355 was more brutal, and generally louder. I didn't expect this at all, that made my day (and the 90€ worthwhile).


Yesterday I finished re-assembling the loop. Tonight I will fill it up and start it up again.


Here's when I am at right now:

(There's one radiator fan missing, I had to remove it because of the CPU waterblock leaking right on it.)

Nothing special except something I wanted to try out: I have assembled a fair number of loops in my time (about a year), every time with the pump making direct contact with either the case or a fan, thus spreading its vibration and increasing noise. Building a new loop from scratch was an opportunity to make the whole system silent, or at least as quiet as I can. I know the pump accounted for most of the noise in previous systems, and read stories about people suspending theirs to get rid of any vibration. That seems like the ideal thing to do. Only I didn't know how to go about it the proper way with rubber / elastic strings. Then I realised that I used to think compression fittings were holding hoses in a shallow manner. By now I fully trust compression fittings to hold hoses very securely, so much so that I know hanging the pump from one would never make the hose "slip out".

This lead me to hang the pump off the hose coming from the reservoir outlet. The outlet of the pump then leads directly to the radiator. Theoratically, any vibration should be absorbed by the hoses coming to and from the pump's inlet and outlet. Will this work as expected? (Answer tonight, but opinions are welcome.)

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By the way, thanks to whoever moved this thread to the build log section!