Thx for you answer.
I have never overclocked any of my current HW, its all stock. My PSU is as you see a Corsair 650W which should do the job nicely regarding the 260. All my other games (Far Cry 2, Fallout 3, Call Of Duty 4, Dead Space, Age Of Conan, LFS etc) works flawlessly.
I'm using NVmonitor and it shows about 70-75 degrees temp on the gpu under load, and not over 50 on system temps so i don't think temps are a problem either
RAM timings, i have no idea what that is, and i can assure you that i have never twinkled with it
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My RAM chips are getting a bit old now though and might soon need a replacement, but as all my other games is working i don't quite feel the need. And as i mentioned, the game worked before when i used 2x 8800GTS cards in sli. Maybe my 260 card just doesent like CryEngine.