I have 8RDA+V1.1. I'm assuming your NB and NB cooler are similar.
Pull the board, flip it over and you'll see the two pins that hold the NB cooler to the board. Pinch the notched ends together and push the pins out. Keep the pins for re-use if you wish. Heat the NB cooler with heatgun/hairdryer and the cooler will twist off easily - revealing the melted-chiclet mess that was a thermal pad. Clean that off.
Check the surface of your NB chip for concavity. Mine was terribly concave. If it is concave, you should lap it flat. If you buy an Iceberg, it comes with two passive copper heatsinks. The larger one makes an excellent sanding block for sanding your NB flat. It took me about an hour to get my NB flat with 600-grit paper.
You can then either use pins to mount the Iceberg, using a good thermal compound such as AS3, or permanently mount it with thermal epoxy. I used pin-mount and AS3.
Microcool offers a kit that includes an impressive NB active cooler and ramsinks for your MOSFETs. I used only the microcool ramsinks, mounting with thermal epoxy.
For thermal epoxy, I recommend Arctic Alumina because it's non-conductive if you get a bit sloppy.
I used a Zalman NB32J passive heatsink for Southbridge. Check both for flatness. My SB was somewhat concave, but not as bad as the NB. The Zalman wasn't flat, sort of like a U-channel, and needed a good bit of metal removal for flatness.
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The above site has good selection, good prices and is absolutely the fastest-shipping vendor I've dealt with - better than Newegg.
Hope this helps!