The RS64-IV or Sstar was introduced in 2000 at 600 MHz, later increased to 750 MHz. Up to 16 MB DDR L2 was supported in the same manner as the RS64-III (19.2 GB/s bandwidth). The RS64-IV had 44 million transistors and was 128 mm² large manufactured on a 0.18 μm process. Unlike POWER, energy consumption remained low, at under 15 watts per core.
For a time, while the POWER line stagnated at half the clock speed of its competitors, the RS64 family was at the top of the IBM large SMP UNIX server line. The integer / commercial workload performance of the RS-64 IV was similar to the Sun Microsystems processors with which it competed, though its floating point power was not comparable to the contemporary POWER3-II, which remained reasonably competitive throughout its lifecycle.
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