To address that thermal layer problem, Glumac engineers adjusted the CRAC system by raising the height of the air-return intakes by 1.5 to 2 feet. That pushed the thermocline layer above the tops of the racks, providing a better thermal environment for equipment located there.

Next up: Once the airflow balance was achieved in the aisles, engineers turned their attention to what was inside the racks. "There's an optimal temperature point where you want your chips running," says Patterson. Scottrade tended to have the hottest, most power-hungry devices in the top of the racks, where they received the warmest air. Scottrade reorganized the racks, moving power-hungry servers lower to balance the heat distribution within the racks.

It also helps that Scottrade's new data center is using energy-efficient servers. The 1U and 2U and blade server models in use at Scottrade sport low-voltage processors, variable-speed fans that operate according to processing power consumption, and high-efficiency power supplies. (Those units come with embedded on ROM, making setup easier.) "It draws less energy, and it keeps the internal temperatures in the boxes cooler," Patterson says.

But there's another advantage to newer servers that data center managers may miss: They run fine at higher operating temperatures than the previous generation of equipment. That means that server racks can run warmer. "Data center operators who take advantage of these higher-temperature capabilities can gain significant energy efficiencies in their cooling infrastructure," says Graves.

Those changes "improved our power consumption [and] our air conditioning costs, and reduced our total costs of running our business," Patterson says. At Scottrade, low latency is critical to keeping its commitment to completing trades fast. It relies on the highest possible server performance to support split-second transactions for its customers. Fortunately, the redesign required no compromises: Moving to a hotter data center didn't reduce performance or affect the longevity of data center equipment, he says. Instead, he believes the changes improved reliability by keeping equipment within optimal operating ranges.