Restriction isn’t as exciting as thermal data but it is a necessary part of the results. For restriction testing we use a Dwyer Manometer and a King Instruments flow meter. As we vary flow we measure the pressure drop across the CPU block in question. A good rule of thumb I like to quote is that a component should be less than 1 PSI of restriction at 1GPM.
All three Koolance blocks we are looking at today have quite similar results. It’s noticeable though that the 390 and 390C seem to be about 10% apart the entire time. I had expected the 390I to have lower restriction because it is a two part construction without o-rings and I assumed that it would therefore leak from input to output. But instead the 390CI is lower restriction. This is perhaps due to the different channel design in the inlet port as that is really the only difference between the two designs.
Even with this few number of blocks it can get confusing as to which is which. Five blocks appear to be the same while the Alphacool seems higher in restriction, and the XSPC is far lower. In order to compare to more CPU blocks that we’ve tested we’ll have to simplify things and only look at the 1GPM datapoint:
It’s clear then that the CPU-390 is a medium restriction block. While it could certainly be higher flow, it’s not so bad as to be a problem.