Thermal Compound or thermal paste is probably the least exciting part of any PC build, but on the other hand, is also one of the most vital. It sits between your CPUs IHS (Integrated Heat Spreader) and the base of your heatsink. You will usually find thermal paste on your motherboards north and southbridge coolers and graphics card cooling as well. Ever since the beginning of time, Artic Silver have been the market leader in regards to thermal compounds, with their Arctic Silver 5 selling by the bucket load.