You tried to overclock your CPU but now your monitor does not start. Oops!!

So, you got the lesson. DO NOT OVERCLOCK your computer.

Overclocking results in change to the voltage profile within the circuitry. This can be minimized by increasing the voltages applied but too much increase can burn up the circuitry. A bigger problem is the heat generated due to overclocking. Which is why the boot frequency did not match and your monitor doesn't turn on. Even if your computer runs after overclocking, it will have a greater tendency to hang. The solution is just open your cabinet and look for the CMOS battery in your motherboard. Take it out and insert it after 15mins. BIOS settings are set to default and you are back in business.