For a rundown of different CPUs, how they work, and what voltages and speeds are the most successful for overclocking, refer to the Overclocking White Paper . Overclocking caveat Do not overclock your CPU if you work with sensitive or vitally important data, since you could experience subtle problems, such as floating-point calculations being slightly off. If stability's important to you and your job, mucking with your system clock isn't a good idea. Maximum PC takes no responsibility for any damage or injuries that may result from your overclocking pursuits. The small die sizes of today's CPUs make it dangerous to push the amount of electricity supplied to them.
Side affects most certainly include increased heat that can lead to electromigration.
As always, don't forget to ground yourself when working inside your computer. Static electricity will kill your motherboard if you accidentally discharge inside your case. A grounding strap that connects your wrist via a wire to a metal surface is best. If you don't have one of these, touching any metal surface prior to touching jumpers, pins, or switches on the motherboard will also ground you. Keeping your cool Heat is the number-one reason CPUs have problems running at higher speeds.