Hello,
Recently I brought back my Power Mac G3 B&W from the dead by purchasing a logic board replacement. Since I was already using a G4 ZIF module pulled out from a Yikes, I decided to get an original Yikes logic board instead of the Yosemite, as it a newer revision of the same board, with the downside of having no ADB port, however. After installing everything in its place I came into some minor issues (wouldn't boot with all 4 dimm modules populated after a memory error warning on the first boot, 3dfx games not working with my voodoo2s which were working before it died and HDDs would not spin up after installing a second OS on the second HDD and switching the startup disk, requiring a shut down). The first issue somehow disappeared after switching some PCI cards into different slots and putting them back on, switching HDD jumpers to Master/Slave/Cable Select (On the first day, both HDDs were on Cable Select and then on the 2nd day, the second HDD wasn't being recognized anymore, only after I switched the first one to Master). I believe one the 3dfx cards might not be working anymore, as I tried only one of them and Glide could not detect the hardware (using 2 cards on sli, the game I tried, Shadow Warrior, would crash on startup with Error type 3 message or it would run on a blank window). I have Mac OS 9.2.2 on one HDD and 8.6 on the other (Shadow Warrior didn't work on neither). I tried replacing the PSU with another one I have spare, but it didn't make a difference on the remaining issues. I also tried looking for firmware updates for this model, but found none. Also tried using a wrapper called MacGlide but it's way too buggy (the games would launch but full of visual glitches). Games that run on the main GPU (a Radeon 9200) with H/W acceleration are working fine (it only works on Mac OS 9.2.2 and when it's fully updated, OS 8.6 currently has the ATI extensions disabled and is mainly used for older games that have issues on Mac OS 9.2.2) My configuration:
G4 400MHz (overclocked to 450MHz with 2 extra fans attached to the heatsink + Arctic Silver 5 thermal compound)
ATI Radeon 9200 128MB
1GB RAM
80GB Maxtor HDD + 80GB Seagate HDD
LG DVD burner
2 Diamond Monster 3D II 8MB sli

These remaining issues don't bother me a lot, but since my B&W died after a cycle of shutting down + power on, I'd like to avoid that as much as possible this time. Any help is appreciated.