Arctic Cooling MX-4 Thermal Compound (4g) $6.51 FS

MX-4 is pretty good, but those who want a little extra cooling power should use Gelid GC Extreme or PK-1 or Thermalright Chill Factor 3, as it doesn't cost much more than MX-4, but it is about 1.5 degrees C cooler for typical (moderate) contact mounting pressure: http://skinneelabs.com/2011-therm...parison/3/ (Phobya HeGrease is the same as Gelid GC Extreme... for the curious, Indigo Extreme is WAAAY more expensive than any other option and imho not worth it when PK-1 and Gelid GC Extreme are much cheaper and almost as good).

Those who don't care about 1-2C differences may as well just stick with MX-2 which is very frequently on sale for less than MX-4.

Arctic Silver 5 is old school... it isn't that great (it's way down there on the Moderate Contact chart, 8th from the bottom; though it does better if you mount your cooler with high pressure... take care not to flex/bend your PCB when applying high pressure mounting), takes a long time to "cure" (way longer than most other thermal pastes), and it's conductive which is a no-no if any gets onto the circuit board. Yeah it's cheap, but so is MX-2.