Drop-In G4 CPU transplant: To G3 B/W from G4 Yikes possible?

Elosha

New Tinkerer
Aug 14, 2025
10
10
3
Europe
Hey there,

I got
  • a G3 B/W logicboard (dunno which rev)
  • a G4 socketed CPU (taken from a G4 Yikes)
from e-waste.

1. Seems I managed to modify the G3 board to work with ATX PSUs directly. However when the board tries to boot, it beeps 4 times. Accourding to lookup tables, this seems to be a firmware error, right?

2. I don't have a G3 to verify what this means. Has anyone already dropped a G4 CPU into a G3 with success?

3. My guess was this might be related to the G4 being unknown to the firmware. Is this true?

4. Means I would need to flash the FW – are there options in software via OF prompt, or would I need to desolder and burn the chip directly?

Thanks for sharing your experience!