Ok, so I just bought another GTX 970 and went SLI to get better performance in F4 @ 1440p.
With one card I got around 28-60fps depending on area.
After adding the second GTX 970 I'm getting about 32-60fps.
Game is unmodded. 1440p @ ultra with godrays low and shadow resolution high and shadow draw distance medium.
FPS in unlocked in game settings and synced in Nvidia control panel to 60, without limit it goes higher in some areas but still drops to 28-29 in some.
Fallout has the latest patch and all my drivers are up to date.
My specs:
ASUS Sabertooth Z77
Intel i7-3770K @ 4.1GHz
8Gb Kingston DDR3 @ 2000MHz
2x Asus Strix GTX 970 OC:d @ 1360MHZ core & 7782MHz memory
Kingston HyperX Savage 480Gb SSD
Corsair RM850i power
I just don't get it how the fps dips so low even with SLI... really annoying.
EDIT:
The lowest I got with the SLI setup was 28fps on the deck of USS Constitution. Checked my GPU loads and they were both hovering below 50%. CPU load was about 60%.