While under development, the X540 was known as Twinville, and it was Intel’s fourth 10 GbE design. The first card (far left) used the Intel 82598 MAC and a third-party PHY. With two chips and a larger fab process, the card consumed about 25W—the maximum allowable from a PCI Express card—and required a fan on the heatsink. After four years, a shrink from 65 nm to 40 nm, and the addition of another port, what would become the X540-T2 consumed half as much energy and was able to shed the fan.