for a 18*c idle temp even with water cooling you have to keep your room under 16*c. Those temps are doable, I ran a i7 950 at 4.8ghz idle at 9*c but that was in the middle of winter with my radiator ducted to an open window. That was using -23*c air to get the cpu that cold at idle, now at 100% load it still never reached over 20*c those were the fun days of overclocking