you spend 600 watt just to cool it down? thats stupid.
buy some server fans and run them at 5600 RPM and you will get the same temperatures with just 30 watt extra.
I have a portable A/C just to cool 2 gpu rigs. It's more like 1200 watts, and a extra 25-30 dollars a month is nothing if can earn extra and increase the life of your equipment. If you live somewhere with jacked up power costs you may be better off just fans. There not nearly as effective though.