I'm upgrading an old MacG4 and looking for some advise. I purchased a NewerTech 7448 CPU upgrade (2.0GHz). Physically installed fine, but now screen (and I'm assuming the CPU) freezes after a few minutes. Re-installed with no change in behavior. Board was flashed to latest BIOS while in OS 9 as instructed. CPU also exhibited this freeze in OS 10.4 and new 10.5. Set the CPU speed down to 1.4GHz which remained stable enough to load OS 10.5. But it even froze at that speed after a couple of hours. I've tried flashing the NVRAM with no success in changing the behavior. I did return to manufacturer for defect testing. Tested OK and they suggested power supply issue so I purchased a used, larger PS. I'm assuming this is a hardware issue as the original CPU works fine when I re-install it. Has anyone had experience with this upgrade or issue?...Thanks

Machine Specs:
Mac sawtooth AGP G4 (originally 350MHz model, 100 MHz bus)
Upgraded to 1GHz RAM
Upgraded PS from original 208W to used 237W