Ok my question is are you having slowness issues or are you just watching the graph in Prex and seeing it not max out? If you are playing fine then stop worrying if it is all jerky and strange then that IS a problem I am playing at 5760x1080 on a single 670 all settings high so 1 screen it should just tear that up at ultra.
Have you used something like GPU-z where you can record what is going on? Have you tested with Heaven's Benchmark or Furmark while recording? I don't see a maximum GPU load here. On top of that, I don't know what fan size is used on the card, but the fan profile looks to be rather aggressive to be spinning over 3k RPMs under 60* C. This would explain your temps being low easily. I have a 7870 with a 25% overclock, runs at 2200 RPM at 65*C, but will drop as low as 55*C at it's max fan speed of 3100 RPM (ambient is about 25*C). Unless you are having major stuttering issues and/or you can verify (unless I missed it) that you aren't logging 100% load, then there doesn't seem to be an issue.