<< can you put 2 chipset fan on both chipsets (north and south)?? >>
Of course you can, but it's not necessary. The southbridge doesn't get so hot that it needs a heatsink, much less a hsf.
The reason the northbridge gets hot is that it connects the cpu, ram and southbridge. Cpu and ram need a fast connection = hot, that's why an improved northbridge can make a chipset much faster (the only difference between KT266 and KT266A is a btter norhtbridge).
The southbridge connects the pci-slots, ide controller and ports, and there aren't nearly as much data passed between those and thus it doens't get so hot and don't need cooling at all.
You can see it on the mobos: all modern mobos at least have a heatsink on the northbridge and many also a fan while no mobos have even a heatsink on the southbridge.