Game runs differently : I have fps drops ONLY when I turn around for the first time, or drive fast through city (probably when new textures are being transfered to VRAM).
When I stay in one place fps rate is much higher on 5970 then on 6970.
Seem logical - 2xGPU, 2 x 1 GB VRAM vs 1 GPU, 2 GB VRAM.
Basically, in 6970 there were less fps fluctuations.
Sadly, GTA IV benchmark shows about 28-30 fps average on both cards.
As there is massive fps gain when I disable shadows, without GPU usage change, I suspect that GTA IV has some own build in shadow processing system that need lot of data transfers, as GPU & CPU are not used in 100%.
I just ordered :
- OCZ DIMM 8 GB DDR3-2000 Kit
We'll see, how this will help.
Next step could be changing the 5970 to 4GB version & or going Crosfire.