How can I tell if I have a dead motherboard or bad power supply? My Dell XPS won't turn on any more. The power light glows amber- it used to be green. I ordered a replacement power supply from Dell and installed it myself, but it still won't power on. I hear a slight fan running but it sits there doing nothing. Is there a surefire way to tell if the motherboard is fried? It is obviously an older computer, but I don't really want to replace the whole thing right now and if I can fix it cheaply enough (under $100) I'll do it.