QualBob, miswiring the front panel can cause this behaviour, e.g. you could be in permanent reset mode. Disconnect everything from the motherboard except the processor with heatsink, ATX power, power switch and case speaker. Reset the BIOS either using the reset link or by removing the battery for a few minutes. If the motherboard boots (to a POST error beep because of no memory or graphics card) then you can start adding the other components.