The overclocking process for the Pentium 4 is greatly simplified due to the locked multiplier present in all consumer-level processors. Sure, you might nab an engineering sample through other means, but for the vast majority of users, Intel Pentium 4 can only be overclocked via an increase to the front-side bus speed.
Since this is a more general guide written specifically for the Pentium 4 Northwood, we're not going into the nitty gritty of CPU overclocking, but if you need a primer, check out our CPU Overclocking Basics article. There are definitely topical references that need to be updated, but the basic information concerning FSB speeds and core voltage is still quite useful.
For our purposes, the first step is to familiarize yourself with your motherboard and its capabilities. The important areas are front-side bus speeds, CPU core voltages and DDR speeds and voltage options, as well as the procedure for lighting up a PC after a failed overclock (many board support a certain keypad press upon boot). Consulting the AGP/PCI dividers and settings is also a good idea, as some boards seamlessly integrate this into the BIOS, while others may require a jumper be changed.
All motherboards are special in their own way, and while most support FSB increases and core voltages through the System BIOS, others use onboard hardware jumpers, dip switches or even software programs, and a few do not even offer any overclocking options at all. Before getting too deep into the process, take the motherboard manual out of the box, dust it off, and get up close and personal with its features, options and capabilities. Like the old guy says on the tube, before you spend your money, spend your time. Since a failed overclocking attempt has an outside chance of damaging data or Windows registry settings, it might not be a bad idea to backup your data.
Once that has been completed and you feel comfortable with the above options, the first step is to increase the FSB, while raising the CPU core voltage as needed. Adjusting the DDR voltage levels to 2.6V or 2.7V (any higher increases the risk of damage) to maintain higher memory bus speeds. Exactly how this is done is a very personal choice, as some like to raise the FSB slowly and taking the time to ensure full stability. Others prefer to go for the gusto and take a 100 MHz Pentium 4 straight to the 133 MHz FSB, and let the cards fall where they may. Pick your poison, as each works well, but either procedure, always keep in mind the higher AGP and PCI speeds that may result with some of the older Pentium 4 platforms.
The choice can also come down to the CPU itself, and since the 1.6A is a virtual lock for the 100 to 133Mhz FSB jump, doing so right off the bat may be the quickest and easiest method of overclocking. Many Pentium 4-1.6A processors can even hit the 2.13 GHz overclock without increasing the core voltage. Those with higher-speed Pentium 4 processors may feel safer moving a bit slower with the FSB, especially at 2.0 GHz and above. It's highly unlikely that a Pentium 4-2.2 GHz or higher is going to hit the 133 MHz FSB, so increasing these speeds slowly is really the only viable option.
About the only real word of caution we can offer is to go light on the core voltage settings, as this is one area where you can do some real damage. Experienced users may scoff, but we recommend that everyone else stays at or below the 1.65V limit. This will limit the adverse effects of an ultra-high core voltage, as well as insuring that CPU temperatures don't get too out of hand.