This Is because the Overclocking frequency that you had set Is out of CPU limitation. By following steps you can secure your system--
- Removed The Power Core From The System
- Closed The Jumper JCLK3
- Plug-In The Power Core & Turn ON The System
- Press "Delete" Key To Enter The CMOS Setup Menu
- "Load Optimized Default" under the CMOS Setup Menu
- Save and Quit the CMOS Setup Menu.
- Turn The System Off
- Open the JCLK3
- Turn On the system