every CoD you have has the stutter there might be a connection there not sure why it stutters on the other games.
I don't think it is hardware related and it's usually something really silly with these kind of issues so I'll just throw some ideas.
like others said it could be a sound issue, since it's mostly CoD do you have stereo mix enabled/disabled? maybe try a different bit rate on it.
when does the stutter happen exactly? anything specific ? explosion? shot fired? or just random stutter even when looking at the sky?. enable lag-o-meter /drawlagometer 1 and look for the stutter (should be a yellow bar) and if there's anything specific happening that might cause it.
does it also happen in SP? you can try creating a dedicated server as LAN in WoW and disable PB and join that server from the LAN filter some people had issues with PB taking pictures and creating lag spikes.
I had some other things in mind but I forgot what I wanted to say