Why would the power supply fail now? It had been running before? (just curious before I spend cash)
Well you did say:
Computer rebuilt because of a strange noise. Ended up being the power supply fan
If the fan was working below speed or intermittently components in the power supply could have been running over temperature. That will reduce thier life span.
One other thing are you wearing an antistatic strap doing all this insertion / removal work? One good zap = a factor of 10 decrease in life for a sensitive component like a processor
