I managed to assemble my shiny new watercooling, so thanks to everyone who helped picking up the components and gave advices
The temps are better than anticipated.
The CPU now idles at 27C and goes up to 34C under prime95
as a comparison, an H50 (I know, I know it's not comparable because of the price) on a slower clocked, 965BE (CnQ enabled) manages to do 33/55 and my previous V8 done 34 - 59C :O
The GPUs became much cooler too. with 32C idle and 50C load I cannot really complain
(stock cooler: 65C idle - 91C load)
I decided to go with the 120mm rad for the CPU loop as going for a bigger rad didn't make any noticeable difference and I've used the jet plate which provides the highest flow.
I'll post some pics and the detailed price breakdown tomorrow if anyone interested