Fisrt off, right click your speaker icon in the task tray (bottom right), then select recording device.
In the resulting window, right click over the Microphone icon and click "Set as Default Device".
Now double left click the microphone icon, go enable your mic boost in the Custom tab. Under the levels tab, crank the slider up to about 80%, or whatever you please.
Your mic should now be functioning perfectly, if not try a reboot. Now to mute the mic so you dont personally hear your fans and yourself speaking, go right click the speaker icon in the task tray again, and go Playback Devices.
Hope this help. I had the same issue and this is what I had to do.
Double click the Speakers icon in the resulting window, click the Levels tab, and scroll down till you see mic, and click speaer icon on the far right.
Now you all should have your mic's working