Yep, that's just poor lighting at work. Note how you (better-lit) show little/no noise, while the wall in the distance and wood paneling at bottom-left both show quite a bit.
The c920 is good, but you need better lighting, bro. Ambient room light won't cut it, if you want quality.
I use a 1200 watt equivalent (4x68W pro-grade CFL) distant softbox flood, and a 300w equivalent close-key. You don't need that much, but a gooseneck or drafting lamp (or clamp-on bowl reflector work light from Home Depot) with a good bulb pointed at you will improve things dramatically. If you want your whole room to show up well, you're going to have to FLOOD it with light. Relying on normal home lighting is going to end up with what you're seeing. Just make sure your bulbs are all color-matched if you can, to make white balancing easier.
Welcome to one reason a number of casters wear Gunnars instead of just using f.lux; getting blasted with light for hours on end can cause eyestrain and fatigue, especially in geeks. And doubly-so if you decide to go with 6500K bulbs (I use 2700K and just white-balance it out; even if it's not as good, the ability to comfortably long-cast is worth it).
