Liquid Flow Restriction

I use a Xylem D5 pump with a standalone reservoir, with the pump being powered through a direct SATA connection from a PSU used only for watercooling components and not part of the test system. The pump is controlled by an Aquacomputer Aquaero 6 XT in PWM mode. There is a calibrated in-line flow meter and Dwyer 490 Series 1 wet-wet manometer to measure the pressure drop of the component being tested. Every component is connected to the manometer by the way of soft tubing, compression fittings, and two T-fittings that have been accounted for when it comes to the liquid flow restriction in the loop.


There are a total of six blocks in this roundup, including a universal GPU block that I had tested at the last minute before the GPU had to be returned! Otherwise my plan was to get one entry each from five manufacturers who were able to provide units in time and so everything somehow worked out. All of these will get dedicated reviews over the course of the next few weeks. As it stands, the Phanteks Glacier G4090AS ends up in the middle but easily in the pack of the top three least restrictive blocks. Those bends and angles in the coolant flow path don't help but ultimately the lower number of fins and thicker microchannels overcame that deficit to a good degree. The end result is a water block that barely taxes a decent pump and is less restrictive than a typical CPU block.