Buzzing Sound with Multiple Headsets

So recently I have been trying out multiple headsets on my computer and no matter the headset, I receive a persistent buzzing sound. The two headsets I have switched between have been the Razer Carcharias and the Logitech G35's. I know the Razer Carcharias have a known issue with the buzzing and I have contacted the support team and they told me to try plugging the USB into a cell phone charger and plugging the charger in to no avail. However, I used the G35's before the Carcharias (I have recently switched back to the G35's because the Carcharias buzzing has gotten too annoying) and they did not produce a buzzing sound. However, now the buzzing sound is occurring with the G35's. Could this possibly be happening because I have used up all the 8 USB ports in the back of my computer and I need to purchase a USB hub or something?

Please help me. I just want a headset to work without difficulty :(