Other World Computing (OWC) today announced it is now shipping an 800MHz Mercury Extreme G4 processor upgrade. The US$269.99 upgrade features 256 Kilobytes of 1:1 L2 cache on-chip and 2 Megabytes of high-speed L3 cache. It is compatible with Apple’s Power Mac G4 AGP Graphics/Sawtooth, Gigabit Ethernet, Digital Audio, Quicksilver and Quicksilver 2002 models. The Mercury Extreme line is completely plug-and-play compatible with existing hardware and software, including Mac OS 9.2 or higher, including all versions of OS X. OWC also offers 1.25-1.26GHz and 1.4-1.467GHz Mercury Extreme G4 models for $499.99 and $589.99, respectively.