I got an XFX 9600GT 512MB as well and no problem at all playing Crysis 2 on a simple core2duo system. Unless your card is dying you should have no problems running the game as it runs perfectly smooth on mine.
This issue can be related to:
- Graphic card over-heating. Look for temperature with HWMonitor or eVGAprecision 2.0.3. Shall not exceed 85 degrees. When I do play Crysis 2, I put it's fan to the maximum, I also overclock the card from 650/1625/900 to 745/1862.5/1150 (core/shader/mem) AND the cpu/ram/fsb to the roof too. These are the maximum stable clocks I've been able to achieve. The card can reach up to 85 degrees centigrade and it doesn't have a single behavior.
- Beta Graphic driver or an old one. Try driver sweeper to uninstall every graphic drivers, reboot, install the latest WHQL driver from nvidia, reboot.
- Outdated DirectX. Update it to the latest version, reboot.
- Power supply failure. Use HWMonitor and look for voltages. They have to stick around their specification (1.95V on the +12V line shows the pus is dead).