Not only do the new chips run at a higher clock speed, but they also include an advanced AltiVec Engine, and a pipeline capable of supporting bus speeds of over 1GB/second. According to Motorola:
Delivering supercomputing levels of performance with revolutionary enhancements to the PowerPC(TM) microprocessor family, Motorola (NYSE: MOT - news) today announced the introduction of the MPC7450 PowerPC microprocessor with AltiVec(TM) technology. The MPC7450 processor, the third member of Motorolais fourth-generation (G4) PowerPC family, is shipping now at speeds up to 733 MHz. Continuing to build on its industry leadership position, Motorolais new PowerPC processors provide best-of-class solutions for the networking, telecommunications, high-end embedded systems, scientific computing, and desktop computer markets.
Designed at Motorolais Austin, Texas technology center, the MPC7450 microprocessor has an advanced, deeper, seven-stage pipeline with two additional execution units, and an enhanced AltiVec engine. The L2 cache has been integrated onto the die for greater speed, and a 256-bit datapath to the L1 cache has been implemented. The MPC7450 processor also supports a large backside L3 cache with a 64-bit datapath, and provides multiple SRAM options. Additionally, the MPC7450 microprocessor implements Motorolais high-bandwidth MPX system bus, capable of achieving sustained bandwidth performance of 1064 MB/sec. which can provide up to 5 times the bus performance over G3 generation processors. Finally, the MPC7450 microprocessor has extensive tool support from compiler, debugger and emulator vendors providing complete sophisticated development environments to go hand-in-hand with Motorolais G4 architectural definition and the MPC7450 processor design.
The AltiVec vector processing engine has been expanded to dispatch two instructions to any of the four AltiVec execution units per clock cycle. This enhancement greatly improves vector instructions per clock performance. Software can also be optimized to utilize the MPC7450 microprocessoris AltiVec technology to enhance performance.
The MPC7450 PowerPC microprocessor is manufactured in the HiPerMOS 6 (HiP6) 0.18-micron copper fabrication process technology, and features a low-power design with three power-saving user-programmable modes -- nap, doze (with bus snoop) and sleep -- which reduce the power drawn by the processor.
You can find more information about the G4 family of processors at the Motorola web site.