I have one of those alphacool xp blocks I got in a job-lot of watercooling bits a few years back - glad I never fitted it! Bad design with an overly restrictive copper grid and the silly right angle going to the impingement holes in the plastic top, presumably to allow space for compression barbs. I use the XSPC Edge atm - great block with lots of 0.3mm thick, 3mm deep, sandblasted fins (around 60 iirc), so lots of surface area and very little restriction. Just a shame they don't make it any more. @Bad_cancer - Imo a finned block is the way to go, especially if you know someone with a slot cutter to make very narrow channels..