I have a Dimension E310. The power button is solid amber and I have all 4 diagnostic lights lit. I can hear and feel the harddrive startup when initially powering up system. Monitor is black screen and has no input (also has amber light). I went thru and reseated memory, processor, modem card, all cables. I went thru and checked power supply (all voltages are correct.). How can I know whether it is the motherboard or the processor that is bad? Or is there other tests that can be performed?