Two thoughts.
1) If you're using the G3 upgrade without a video card installed, you may need to install a PDS terminator in the video card socket. Apple made dire warnings about operating the NuBus PMs without anything in the PDS slot.
2) When I assembled a PM8100/110 with a NewerTech G3 and PDS passthrough, the HPV card gave me a lot of trouble if it had VRAM SIMMs installed. Try the video card without any VRAM SIMMs, if you have not already. I suspect that there's just not enough power available in that slot for the G3 upgrade, and the HPV card and the additional VRAM.
1) If you're using the G3 upgrade without a video card installed, you may need to install a PDS terminator in the video card socket. Apple made dire warnings about operating the NuBus PMs without anything in the PDS slot.
2) When I assembled a PM8100/110 with a NewerTech G3 and PDS passthrough, the HPV card gave me a lot of trouble if it had VRAM SIMMs installed. Try the video card without any VRAM SIMMs, if you have not already. I suspect that there's just not enough power available in that slot for the G3 upgrade, and the HPV card and the additional VRAM.