I have a dual core 5 ghz computer with 4 gig ram, with radeon hd 3650 512mb ddr2 memory for a graphics card and asus motherboard and when i play stalker clear sky it keeps lagging. I tried patching it, lower the graphics settings and right now i am on low level of graphics. What should i do to stop it lagging. oh and by the way i have direct x 9.