If you're looking for a moderate overclock with very low noise and very little cost and trivial installation, check out the Arctic Cooling Freezer 7 Pro. If you're more interested in the highest overclocks possible then get the Nirvana or Tuniq. Between the Nirvana and Tuniq Tower I personally prefer the Nirvana because all the differences, though very small, are in its favor (2 degrees lower, 2 dB less, $11 less last time I compared reviews and prices).