The fans supplied with the XE models are all notoriously poor, as you may (or may not) know. That's why the processors come underclocked to 800MHz... There haven't been any issues with overheating on my board, but I believe that clocking the G4 at its native 933MHz with that fan would be a mistake.
I would have replaced the fan by now, except that that invalidates the warranty, apparently, which wasn't a risk I was willing to take.
