allthatglitters,
Even WD-40 works fine for fans. I would not worry about the article. Usually dust buildup in the computer will make its way to the fan shaft and start scratching the inside walls of the shaft housing. It takes very little time for the shaft house to get wallowed out. (It is made of plastic.) At that point all you can do is replace the fan. I have known people that have used WD-40 as a cheap fix and have not had problems. Just do not squirt it out of an arisol can. Use a rag to apply it. (You do not want excess dripping on your hardware.)
With the Northbridge, the fan is not critical. If your computer starts locking up, you could always get a larger heatsink and fit it to the Northbridge for some silent cooling. (The only time a fan is really needed on a motherboard's northbridge is if the motherboard uses onboard Video or is being seriously overclocked.)
Take Care,
Richard