I'm planning my very first custom loop for my upgrade this summer. I'm going to replace my entire system this summer with the release of Skylake-X, all I will take with me from my current system is my GTX 1080 Ti FE, Samsung 960 Pro 1TB m.2 SSD and my Seasonic Platinum 760W PSU.
My main goal with water-cooling is cooling efficiency. By efficiency I'm not aiming for the absolute best cooling performance, I'm aiming for efficiency. I want the best combination of noise and cooling performance. The most irritating thing with my systems over the years is the noise. According to the Decibel Meter-app on my iPad Pro the noise from where I normally sit at my desk is about 42 dB idle, and 48-50 dB under load. This is way too loud.. I want to bring it down towards 20-25 dB idle (pretty much inaudible from my experience) and max 35 dB under load (barley notable). It's clearly the graphics card making the most amount of noise.
I'm thinking about going with Phanteks Enthoo Evolv Tempered Glass. What kind of blocks, radiators, fans etc should I be looking at in order to be able to sufficiently cool a Skylake-X 6-core CPU overclocked to ~4,5GHz and a GTX 1080 Ti FE while still being able to keep the fan and pump RPM at a minimum? I know it's hard to comment on a upcoming, unreleased CPU but lets use the equivalent Broadwell-E 6-core CPU as baseline.
As one who have never gone with a custom loop before I don't really have much experience with cooling efficiency with custom loops. I've used my share of AiO's/closed loops but I suppose those slim tubes, that thick fluid and those thin radiators don't compare to the options you have with a custom loop, not at all.