You said: "I am stable at 100 mhz on the core clock but when I set at 100 mhz when play for some minutes the display driver crash"
This is nonsensical, an overclock cannot be both stable and cause driver crashes.
An increase in voltage would most likely solve the issue, however I think the GTX660 Ti (and GTX670's) are voltage locked at 1.175V, There is a BIOS that allows 1.212V for the GTX670 but I'm unsure if such a BIOS exists for the GTX660 Ti.
Processors overclock to different levels, even within the same model or on the same silicon wafer, that's why some people reach higher overclocks than you can.
Sorry I was confused, I meant stable at 90 Mhz but when set to 100 mhz then the driver stop working, I will be looking for this bios.