frame drops for dungeon boss fights (980Ti sli)

just like the title states, im getting frame rate drops during boss fights. i didnt have this issue until maybe two weeks ago. normally i would get 144fps (locked) during dungeon runs. now i get 144 during the run until i run into the mini/main boss. im ranging from 75-82fps during the fight if im facing the boss but if i look away from the boss my fps goes back to 144fps. its extremely odd and i have went to get lengths to try adn fix this issue.

i have uninstalled drivers, rollback to older drivers a few times, formatted my pc and contact evga about this issue and did what they have suggested. none have really resolved the issue fully. psu usage is on high performance and so is my gpu's in sli.

pc specs:
win7
i7 4790k
16gig ram
triple monitor setup 5760x1080@144

im willing to try any suggestions to see whats going on and how to resolve this fps issue.