The first thing I would try is disabling one of your graphics cards. Crossfire is messed up on all the AMD cards before the R290x, and doesn't really speed up your games. FRAPS/benchmarks will report a much higher frame-rate than you're actually seeing. In reality, your monitor is actually getting a lot of micro-stutter and runt frames. They expect to have a frame-pacing fix for this in late January, but for now, crossfire is kind of useless.
Try that and see what you get. I have a 7970, and tried out Skyrim briefly with Vireio 184.108.40.206. I couldn't get it quite working right, but the frame rate seemed pretty high at 1920x1080 w/ 8xAA and 16xAF, so it seems a single 7970 should easily handle it if properly configured!