I have a G5 desktop that will turn on but won't initate. There is not ring (start up noise) and nothing shows up on the monitor. The fan progressively gets louder but the situation doesn't improve. I've tried starting it with out the case on but to no avail. This problem has happened a few times in the past year or so but when I hard powered it down it would start up again fine (happened rarely). I took it to the MAC store and the girl said it was my logic board. Just wanted to get some other feedback. Thanks.