I have had this down to -40C no problem without load, as with any phase change cooling system there is a lot of heat given out by the compressor and heat exchanger so it was a challenge to work out the best way to cool the unit and stop the alarm going off at 40C (compressor heat not the CPU heat). Finally I sectioned the two functions of the case. Air input to motherboard by 200mm fan and hard drives by 120mm case fans, extraction balanced by 2 x 80mm and 1 x 120mm fans in top of case. For the phase change cooler tried 2 standard air in fans on the exchanger and then fans drawing out on a side panel. Reversing this and putting the system under +ve pressure works better and variations are much smaller. So 2 x 200mm input fans at approx 140cfm with an output 56cfm fan at the heat exchanger and also through the PSU. Works like a dream and is well stable. Strangely found that allowing the unit to power off itself then restart by keyboard means it reaches temp in a couple of minutes. Much faster than a cold start. Don't have a clue why. More pics to follow