Micro stuttering without FPS drop

[StrejdaTom]

Hello, I decided to ask for your help with my ingame problem. I am experiencing micro stuttering without FPS drops. I usually have around 120 - 60 FPS outside the cities but I experience small 0,1 sec long micro stutters when I run through the locations.

I tried some things already: Reinstalling game, updating video and audio drivers, turning all graphics settings to low, turning vsync and tripple buffering on and off in catalyst, trying D3Doverrider, turning frame limiter on and off, running memory test and HDD test, checking my CPU, GPU, motherboard and HDD temperatures, setting audio quality to CD (lowest). My game recognizes my GPU well. I also tried switching memory sticks to other slots. I checked my background process, did disk defragmenting and virus/adware/spyware scan.

EDIT: I tried running Radeon Pro but it made no changes.

Stutters dont occur in any other game I play - Guild Wars 2, SWTOR, Battlefield 3.

My pc: AMD Phenom 4x 965 Black Edition 3,4 GHZ
Ati Sapphire HD 6850
8GB ram
HDD 640GB Western Digital
650W OCZ power supply
Windows 7 64-Bit

Please lets avoid judgements about how AMD, ATI and OCZ sucks etc.. I never had problems with AMD, ATI and OCZ before in any other games so I dont feel like switching to Intel, Nvidia, Fortron.

Any ideas? Thanks for any advices!