A method of cooling a heat generating enclosure includes setting a speed of each fan in a first array of fans, wherein each fan in the first array of fans is a first size, is disclosed. The method further includes measuring a process variable. The method also includes calculating a cooling strategy based at least in part on the value of the process variable. The method further includes setting the speed of each fan in the first array of fans or the speed of each fan in a second array of fans, wherein the second array of fans is in series to the first array of fans and each fan in the second array of fans is a second size, and wherein the speed of each fan that is set in the first or second array is set to implement the cooling strategy.