Alan Goodyear

A: Every chip on a PC's motherboard produces a constant clock signal-typically at 133 MHz, 100 MHz, or 66 MHz-and much of the data flowing around the motherboard moves at that speed. Overclocking is the practice of adjusting the motherboard's clock speed so that the CPU runs faster than its original speed.

The same clock signal drives the CPU, but since most CPUs move at much faster speeds than other motherboard components, the motherboard's clock signal is multiplied to achieve the required speed. So a motherboard running at 100 MHz will accommodate a 350-MHz Pentium II CPU if the CPU clock multiplier is set to 3.5 (3.5 times 100 MHz is 350 MHz).

Since most motherboards support a number of different multiplier settings, a CPU can often be run at a faster-or overclocked-speed. Changing the multiplier is easy: Most motherboards let you change the settings either through jumpers on the motherboard or via settings in the CMOS setup program. But the most important question you asked concerns safety. I'm sure AMD and Intel would like nothing better than to sell more chips, but their disapproval of overclocking is by no means just marketing hype.

Running a CPU faster than its designated speed carries risks: A machine that performs hundreds of millions of operations per second leaves little room for error. More seriously, higher speed produces greater heat, very possibly more than your system was designed to accommodate, which can crash your machine or even destroy your CPU.

I know many people who have successfully overclocked their systems, and they claim that the risks are minimal. I also know people who have burned up an expensive CPU while experimenting with overclocking. Being cautious by nature, I don't recommend it. If you're considering taking the gamble, do your homework. Two places to start are www.sysopt.com and www.overclockers.com.