note that there are a couple of boards on the market that already passively cool the nf4 chipset. here's one:
as for cooling your chipset, you certainly can use the swiftech unit, but you would have to dremel a few rows of pins off. you would also need good airflow to get that to work, these chipsets are hot! you could get one of those PCI fan bracket deals, or maybe one
of these.
another option - you could mod a cpu heatsink. here are a few threads that should point you in the right direction:
http://www.xtremesystems.org/forums/...ad.php?t=73086
http://www.xtremesystems.org/forums/...ad.php?t=73845
http://www.xtremesystems.org/forums/...ad.php?t=61809