I have (had) a mac cube. It used to work. I was using it about 2 years ago, and then never really gave it the time of day, so unplugged it and put it in the closet. I took it out and it wont power on. I know this is a vague question, but are there any known problems with them? I built PC's all the time. So far I have switched out the ram, and nothing has happened. PSU?