Most Peg1 mainboards can't accept a G4 CPU. This is a known issue of the Artica chipset. The CPU speed is set on the CPU card itself. G4 modules were never officially sold for Peg1, at least not in high quantities, AFAIK. If you want a G4, better trade-in your Peg1 for a Peg2/G4. Pegasos2 CPU modules can't be used (neither G3 or G4) in Peg1 boards.