Silent case fans, CPU fans and graphics card fans are a way to get a PC reasonably quiet, but even the quietest fans still produce an audible noise. Some manufacturers have developed sound proof mats to be placed on the inside of the case panels of a PC to reduce the noise made by gans even further. The mats usually have a self adhesive side, and there are sets available especially designed for specific cases. The generic sets however contain a number of large mats that can be cut down to size with a hobby knife and placed in to the case. We have tested three widely available kits to see if using mats will actually improve the sound levels of a standard PC.