The low flow rate (0.5-1 GPM) performance of the MCW5000-A is excellent, and then there is very little improvement between 1 and 2.5 GPM. This is reminiscent of the Innovatek rev3 waterblock and is, I believe, caused by a thick base and not using a center inlet. When you consider that many Swiftech users have cooling loops that contain multiple waterblocks (CPU, GPU, and northbridge) and 3/8" ID tubing, the performance curve makes a lot of sense. In essence the MCW5000-A is "tuned" for the flow rates that Swiftech customers are likely to have in their loops.



Link: Pro Cooling