I got really up and down usage with 2x580's sli and i72600k @ 4.2ghz.
Usually while looking into a big room of people the usage would go from 90% to 40% on both cards with a signifigant frame drop into the 30s or 20s.
No matter what settings i had high or low it would drop significantly in these areas.
Im using the latest drivers and even with just one card it still happened although not as much as the frames were lower to begin with obviously with less power.
As soon as I got into the jungle city it seems to have gone back to normal with gpus pushing 90% and constant 70 to 80 fps with mixture of med and very high settings.
It also happeneds during the cut scenes, a gpu drop and frame drop.
I figured CPU bottleneck so I overclocked to 4.5ghz but it had no change.
I have had this in a few other new games lately and its getting really frustrating!. Are games just getting to CPU dependant these days?? Do i upgrade the cpu?? I would have thought it was powerfull enough??
Any thoughts or anyone having the same problem?. thx