Tuniq TX-4 1ml Heat Conducting Thermal Compound Paste Grease
This fine offering from Tunig is rated at a thermal conductivity of six point five watts per meter kelvin (6.5 w/m*k) and in tests performs among the best of the best. It's sold with a hard plastic applicator and although the paste isn't hard to apply, it would be easier if the applicator were more flexible. It's non-conductive and non-corrosive, thus protecting components in your PC from damage along with a low bleed under pressure for a longer effective life. All-in-all, this is a great offering whose sole downside is not the compound itself, but the applicator that it's packaged with.