Corsair Hydro Series H90 Liquid CPU Cooler Review

At stock CPU speeds the Corsair H90 was averaging about 800-900 RPMs between idle and load, in a similar fashion to the NZXT Kraken X40, consequently the acoustic performance was identical. The Asetek pump unit was almost entirely silent. The only time you will ever hear it is on system start up when it has to “warm-up”.

With overclocking we could definitely tell that the fan Corsair provided was quieter than the NZXT Kraken X40’s fan. This is probably due to the PWM range being 800 to 1500 not 800 to 2000 RPM like on the NZXT Kraken X40. Consequently the fan speeds will be lower as PWM speeds are done on percentages. So if both coolers have identical cooling performance, 60 degrees for example, and both fans get set to 50% PWM speed at that temperature, then the Corsair H90 will spin at about 1000 RPM while the NZXT Kraken X40 will spin at about 1100RPM. This is just a crude example but it explains in basic terms why the Corsair H90 was quieter than the NZXT Kraken X40.