Hey i have been facing this problem from a quite a while and so i decided to report this to you guys. The problem is with my graphic card GTX 460 Hawk @ 900mhz. Now whenever i try overclocking the speed does not go beyond 900 MHz and whenever it tries to cross the 900 level it crashes down and i have to restart the system. I have checked various reviews from the various websites and all of them claimed that it can be stable under 1GHz but it does not under my case. Any possible solution to help me out of this.