[syss]

ASRock's last surprise comes in the form of their 'Dehumidifier' function. This is a very odd feature, especially as it is inappropriately named for the western hemisphere, where dehumidification has only one specific meaning of actually taking water out of the air. Let me take you through the ASRock usage scenario:

You have a PC in a very humid climate, where humidity is in the high 90%. When you use the PC for gaming, the temperature inside the case rises. As air gets warmer, it can hold more water.

Therefore, if we have (for example) 4 grams of water in a case at 40ºC, the specific humidity of that air is greater than a situation where we have 4g of water in a case at 60ºC. But at 60ºC, the air can hold more water (say 6g). When the PC is turned off, or the localized air gets cooler, the air inside the case can get cooler, and when the air reaches 100% specific humidity, the water vapor leaves the air and condenses on components. ASRock's Dehumidifier function makes the PC spin up the fans for a periods of time during the day to remove the hot air that has accumulated during the day from the case, and replace it with cooler air, but at the same time the hot air takes away the extra water vapor with it.

It can get confusing as well if you consider where the extra water vapor would come from. Scientifically, it deals with the balancing of specific humidity across two adjacent temperature zones. Using arbitrary numbers, consider two pockets of air close to each other. Each holding 2g of water vapor (so 4g total), but the first pocket of air (A) is at 40ºC, with a specific humidity of 100%. The second pocket of air (B) is at 80ºC, with a specific humidity of 50%. The water vapor will migrate from A to B, in order to balance the specific humidity. This would mean that in the end, A would still be 40ºC (assuming no heat transfer), but hold 1g of water with a specific humidity of 75%, and B would still be 80ºC, but hold 3g of water with a specific humidity of 75%.

If suddenly the temperature of B dropped to 40ºC, then 1g of water would condense out of the air, leaving it with 2g of water (specific humidity of 100%). This is the scenario ASRock are hoping to avoid with the 'Dehumidifier' function. Perhaps 'Dehumidifier' is the wrong thing to call it, but it is there if this is your scenario.

(For completeness, A and B would again equilibrate to 87.5% relative humidity (1.5g of water each) at 40ºC. There is then the possibility that they would reabsorb some of the condensed water back until none was left. Please note I was using arbitrary numbers to showcase a point, rather than exact calculated values for a given volume)