I have recently acquired a brand new Logitech G930 headset. I installed the software from the website, and found that the sound works from it (version 8.40, by the way). Great. However, it doesn't work for anything else. I have tried it on an old Windows XP machine that I have, and the headset works on there. It's just on my $1500 gaming machine that it doesn't work. Amazing.
I've tried it both while charging and while not charging. With and without another headset plugged in.
I don't think it would be useful to provide specs, because the G930 bypasses sound cards, being a USB headset. However, if I'm wrong, please tell me so.
Also, I'm running on Windows 7 Ultimate x64.
Note: I'm actually dual-booting Ubuntu 12.04 on this machine, so if anyone thinks it would be useful to try it there, please tell me.