Tried Duvar's suggestion of setting low cpu priority in task manager.
Cpu low priority.
Frames, Time (ms), Min, Max, Avg
10039, 120000, 57, 115, 83.658
Default.
Frames, Time (ms), Min, Max, Avg
1477, 20951, 28, 103, 70.498
Utra settings, x2 msaa, HBAO on, post aa off, 1920x1200 res. 4770k '4.5ghz, stock speed gtx 670's in sli. One boosts to 1189mhz, other at 1150mhz.
Cpu low priority.
Frames, Time (ms), Min, Max, Avg
10039, 120000, 57, 115, 83.658
Default.
Frames, Time (ms), Min, Max, Avg
1477, 20951, 28, 103, 70.498
Utra settings, x2 msaa, HBAO on, post aa off, 1920x1200 res. 4770k '4.5ghz, stock speed gtx 670's in sli. One boosts to 1189mhz, other at 1150mhz.