Johnny's I believe was done using phase change cooling on NB. Will point him at this thread tho and he can explain.

512 was hit here using the stock NB cooler and ~ 1.88 vMCH. Only "additional" cooling was some dry ice pellets piled ontop of the NB cooler. This dropped NB temps to ~ 25deg (probe on side of the sink)
Slapping a waterblock on would probably give a similar effect would imagine chilled water would give better results still.
Not really extreme cooling lol. Only mods on the board are vFSB and vMCH. vFSB is still pretty much stock afaik