Apple Power Mac G5 Desktop "orange light disk" Questions

light from orange to green in usually about 1-30 seconds after you turn it on, now it stays on orange FOREVER, sometimes as long as 30 minutes, before turning green (which is when it shows up on my PC

...orange light come on at the front. When I switch on, more lights come up but there is no start up gong and no display. The fans kick in but that's all. Yesterday after a while the fans began to run ...