I've had the same issue with mine. It seems like it comes and goes and for the most part is clear. Try reinstalling audio drivers and going through the "setup" process in Windows. I've also noticed that when software-controlled (motherboard sofware), it seems like the input level is boosted. I know you can boost through windows to some degree, but it's not always perfect.
I was definitely expecting more out of the mic considering how much people rave about them and how much I paid (granted, I paid less than retail - got it through massdrop).