A relative gifted me an old PowerMac 8600/200, which originally came with a pre-G3 PowerPC 604e CPU, but had been upgraded to a G4 by swapping out the ZIF CPU card. It definitely gave a circa 1997 machine (original OS was either MacOS 7.6 or 8.0) a new lease on life and the ability to run OSX 10.2 Jaguar, (albeit slowly and after a serious RAM and HDD upgrade).