IBM POWER5 processors
POWER5-based servers, which supported 64-way SMP and up to 512GB of main memory.
POWER5 (code-named Squadron) and POWER6 processors was planned to have an ability called "Fast Path", that took over tasks that software currently handles more slowly. The acceleration feature speeded up several communication tasks, including the TCP/IP processing used to read and write data on the Internet, and the Message Passing Interface (MPI), used to harness clusters of computers into a collective supercomputer. And the chip accelerated virtual memory subsystem, a frequently used operating system feature that manages how higher-speed regular memory can be expanded by using slower but bigger hard drives.
POWER5, which was built initially with 130-nanometer (0.13 micron) features, also featured "simultaneous multithreading," a feature that allowed a single chip to act as two.
IBM planned to use POWER5 in "blade" servers as well, super-thin servers stacked densely like books in a bookshelf. POWER4 produced 125 watts of power, but a blade processor is constrained to about 25 to 40 watts.