I never had a problem running 10.4 on a beige G3. It takes standard PC66 SDRAM and has no problems running PC100 or PC133 modules. If you want to max out the RAM to 768MB, you need double sided 256MB modules, the same required for Intel 440BX motherboards. I think its chipset configuration was unique as the B&W had a 100Mhz memory bus and a newer system I/O chip. The machine was bizarre because it was old world, but officially supported MacOS X up to 10.2. In terms of PCI cards, I have found that the earlier pre-G3 PCI machines tended to have a lot of timing problems since they had a weird bus divider (50Mhz memory bus to 33Mhz PCI). The beige G3 has a standard 1/2 divider.

The Wallstreet G3 always seemed wonky... period. That machine did weird stuff with the PMU, particularly when the PRAM battery went bad.