I have no previous experience with those products (Headset BeyerDynamics and microphone Modmic).
One possible way forward is to contact the supplier of those products to ask for advice. By the way, have you tried your troublesome headset/microphone in other PC? Are there some settings in your PC that could adjust (lower) microphone sensitivity/gain in audio properties?
If the conclusion is Electromagnetic interference (EMI) using your headset and microphone together with your PC, one possible solution could be adding a separate sound card into your PC. On forums some suggests the noise issue is caused by to low power supply to the microphone through is connection, and therefore the microphone is 'malfunctioning', that is picking up noise from PC.