GX100 with solid orange power indicator

I have a GX100 low profile that will not boot, no video.  Power light is solid orange.  I rfemoved all possible hardware via power cables and signal cables(riser assy with sound card and modem, floppy, hard  drive, cd, etc, ) memory (one at a time), no change  There are no beeps or video.  NIC lights on motherboard are lit, and LED on riser is green.  I downloaded the service manual but that only seemed to cover assembly / dissasembly, no beeb / light codes.  Caps by power supply looked good.  Hard drive spins up.  There is no diagnostice LED assy on this motherboard that I can discern (GX100 466 celeron board).  Hate to shotgun by buying power supply and system board.....