Water has much better thermal conductivity than air so significantly warmer water can provide equivalent levels of cooling. Also, most computer components are

Water has much better thermal conductivity than air so significantly warmer water can provide equivalent levels of cooling. Also, most computer components are designed to be air cooled in an office setting so they can get fairly warm with little damage. In other words to keep an 80w CPU at 45 to 50c might take water at 35c but air at 20c. If the outside air is 40c then then you only need to actively drop the water 5deg where air needs to drop 20deg and cooling systems are much more efficient for small changes in temperature than large ones. You can probably find many cases where air temperature water is perfectly acceptable where you would want chilled air to do the same thing. PS: 40c = 104f and most cpu's are fine at 50c most are still ok at 60+c. If the outside temperature is more reasonable you can often get away with passively cooling water systems where air needs to be actively cooled. You can also combine this with other methods aka if a local lake can give you water below 30c most of the year you might be able to use a passive cooling system with water even if you would need to actively cool air.