What's an NB fan?
 

I recently got an error message from AbitEQ (I have an Abit Fatal1ty AN8 mobo) giving my an error message. Here is the message:

[ErrorRecord]
2009/03/01 08:57:13 Warning:=NB FAN: 20RPM

One of my 120mm fans has been making noises so I am kind of expecting it to croak sometime. I am really not looking forward to replacing it because it is in a very tight spot. It is one of the things I hate about my case. The fan is at the front in front of the hard drive bays. However, the bays themselves are not removable. It was a real PITA getting the thing in when I built this computer four years ago. It will probably be next to impossible to get it out. When I look at AbitEQ now, the NB fan says it is going at 3480RPM. Is it something I have to be worried about?

Just dont play around with cooling. When things get hot they REALLY reduce the life of the component.

Northbridges are getting hot these days. They have to deal with ALOT more and even at times handle 3D work.

A 120mm case fan in front is most likely not plugged into a fan header on your motherboard, is it? Mine is plugged into a 4-pin MOLEX plug on my PSU. Unless it's plugged into the motherboard, AbitEQ can't monitor it. NB fan is a designation for the cooling fan on the northbridge chip, which would be a very small fan (25-30mm was my last). My current board has a passive heatpipe cooling setup on the north and south bridge. That's what I'd check.