I have a Dell Optiplex GX270 and when I turn it on, it almost immediately looses power and shuts down. The one time I did get it goin was just for a second and when it started up, it said that it previously shut down due to thermal event. This would lead me to believe that one of the fans is not functioning, but I do get motion in them when it powers up. The next thing to me would be the power supply. Any opinions?