Here is the stock heatsink.
I have been experimenting with a zalman passive heatsink, and also some thermalright ramsinks (from an 8800GTX kit) and also, running it bare...believe it or not, it runs at under 45c bare, with just a low rpm fan blowing on it, and with a slight overvolt.
The cooling that I'm using on the Northbridge is just a standard Dangerden Maze4 Intel Chipset block like this one.
