Framerate hiccups and audio skipping

So at first I thought it was a problem with Dragon Age that I recently purchased off steam. At first I could play it perfectly on all max settings: no skips, drops, whatever. Then one time I alt+tabbed while playing to another windows as usual and when I went back to the game, but computer hasn't been the same since. The game's framerate will hiccup after every few seconds, and dialogue audio will skip from time to time. I thought the game was messed up.

But I just booted up Jade Empire from steam as well, and it's having the same issues. My PC is fully capable of running these games with a Radeon HD 5870 2GB, i7 930 @ 2.8ghz, 6GB of RAM, running at 1920x1080 dual monitors with Windows 7 64-bit. Problem with steam? I thought so at first, but now it seems like my podcasts I play in iTunes skip occasionally as well, although no where as near as often as when I play games. Sometimes it even sounds like my audio is circuit-bent. Really weird.

I just recently built my first computer maybe a couple weeks ago. I already checked the motherboard audio drivers and those are all up to date. So what gives? Why has my dream computer that I finally got to build now giving hiccups in the framerate for games and audio skips seemingly during any activity? Is this a software or hardware related issue? I really really hope it's software and not a bad motherboard or something frustrating like that.