Over all the Aquabay M4 performed much better than I had expected, even considering it was tested with a "Firecracker" of a drive. The question of needing a water cooler for your HDD can be measured in the life expectancy of your HDD. Less noise from fans and slightly less power consumption. A quote from our friend Viper John still rings clearly in my head when he stated " For every 10°C you increase a discrete parts (memory chips, cores, MOSFETs, ICs, etc) average operating temperature you cut its lifespan in 1/2 what ever that given lifespan may be. Conversely for every 10°C you lower the average operating temperature you double the parts lifespan".
Given the price per performance of the M4 it’s not an expensive purchase. This is of course you are already running a water cooling system. Let's not forget that this cooler was added to Thermaltake's Aquabay series and is intended as a add on. Those running a 1/2" tubing system will be left out; the tubing of the cooler is only 6.5 mm (1/4") which may restrict the water loop to much. Not for Thermaltake kit users only, those running 9.5 mm (3/8") can add the M4 into their water system as well. For a simple design and priced just right I believe Thermaltake should be proud to add the M4 to its Aquabay series.