[Northbridge fan] MSI K8N Neo4-F

If you own a MSI K8N Neo4-F motherboard, I would like to know how fast is your northbridge fan spinning? Mine was like 8xxx rpm when I first bought it, but it just keeps decreasing to now below 1000 rpm. Is there anything wrong? Should I replace it?

I don't have your board, but a decrease of 7000 RPM on fan speed most certainly sounds like a bad fan. The NF4 chipset runs very hot, so I strongly suggest you upgrade your cooling. Good luck with it.