I've got a Scan system. The MoBo is a IC7-Max3. Recently when starting from cold I've noticed that the Northbridge fan makes a kind of rattling sound, which lasts for around 1 minute. It then goes away, and doesn't happen again whilst the PC is on, which in my case can be for up 2 weeks. Sound I be concerned?, or is this OK. The system is around 6 months old.