I'm trying to remember how to get all the extra options up from CLI - in gnome, you access them from the volume control. The mic-boost is not always visible. Sometimes there is a switch to disable it. Sometimes it is not available, period. (You have intel, which is promising, but ATI-fiddled, which is not.)
Open a terminal and enter the following:
lsmod | grep snd
I need the whole output of the first two and the block about your soundcard for the last one. When you copy it over, include the line where you entered the command.
Test the mic in some audio recorder, not skype. Skype is closed source so there is no way to tell what it thinks it is doing.