Mind if I chirp in...
One very very important fact to keep in mind with direct core phase change , i.e., Vapochill style, the fact that the refrigerant is in a state of phase-change, while being in the "block" or evaporator. What does this mean? Well for one, it means that it's boiling, which means it's fluid and gas mixed..... This is not a good thing, when the evaporator is as small as it needs to be for this job, because every little bubble in there touching the side, means a loss in thermal conductivity.
With running a significantly larger coil shaped evaporator, submerged into a secondary refrigerant, you will still get that phenomenon in the primary refrigerant, but the added surface area of the much larger evaporator will greatly negate the negative effect it has on thermal transfer. now you have the secondary refrigerant going through the "HOTSPOT" i.e. the block on the CPU, and this time round, there is no changing phase. 100% thermal transfer at all times.... This is the biggest benefit to chilling liquid with phase change. more practical ones is the ease with which you can now chill more than just one CPU......
To set some facts straight, with regards to the de-humidifier. They are designed to run 24/7. The reason for this is plain and very simple, the compressor has a nice 11" fan mounted right above it, hens nice fast moving air all the time. And that is all it takes to make any hermetic system run 24/7.. Also, a thermostat is needed(and recommended) only if you wish to have the ability to set the operating temp to a value other than maximum cold... for instance using it's vastly superior heat moving capacity at above 10ºC, to comfort say an cluster of 10 PC's, all at once.
What I meant to be removed from the De-humidifier is the humidistat. That is a device that acts on relative humidity. it could care less what the temperature is, and thus it needs to go.