> In August 2008, Intel conducted a 10-month study to assess the effectiveness of using only outside air to cool a data center. The temperature range was 64°F to 92°F. Humidity varied from 4% to over 90% and changed rapidly at times. No increase in server failure was observed.
A certain amount of humidity helps to prevent issues with static electricity. And unless you're pouring water directly across electrical components, there's really not a problem.
I don't know whether 65% humidity is going to hurt a server, but evaporative cooling doesn't work well if the relative humidity is high. So maybe it's a good idea in dry climates, but I can't see it being very effective in the midwest of the US in July/August.
http://www.energystar.gov/index.cfm?c=power_mgt.datacenter_e...