[Note: There are inherent risks when performing any overclocking exercise, such as long term CPU degradation, serious heat issues and a chance that AGP or PCI peripheral cards can be damaged. Also, many manufacturers' warranties may be voided if you attempt to overclock your system. Users need to understand and accept the inherent risks before attempting any form of overclocking. - ED]
For as long as we've had personal computers, overclocking a low-priced processor to match the speeds of higher clocked (and higher-priced) models has been a popular endeavor for many. Many old-timers can regale you with stories of their incredible overclocking feats of bringing a 286 processor to a full 18 MHz, which were unheard of heights for that particular age. The same goes for the 386 and 486 processors, which with the right mix of motherboard and user skill, could also be overclocked marginally. This may seem rather strange in this day and age, but jacking a 486-50 to 66 MHz was quite the relative performance jump.
While overclocking was really a niche pursuit for older processors, the craze really began with the Intel Celeron 300A, which could be transformed into a 450 MHz CPU by simply raising the front-side bus (FSB) to 100 MHz and tweaking the core voltage if needed. The Celeron 300A is really the point in time where CPU overclocking came out of the closet and started to become a more mainstream pursuit. Popular overclocking processors like the Pentium III-500A, Pentium III-700 and 750 and Celeron 533A, 566 and 600 came and went, with each creating a groundswell of support, as well as the usual competition for high clock speed among users.
The main criteria that transforms a basic Intel processor into an overclocking demon seems to be a combination of a newer, smaller core design, coupled with Intel moving platforms to a higher FSB speed. This scenario creates an environment where even general users can take a basic processor, and simply ramp it up to the next step on the FSB ladder.
It had been a long while since one of those "special processors" has come down the pipe, but thankfully that day is well upon us. The Pentium 4 Northwood core provides the required "new core" ingredient, while many highly overclockable and 533 MHz-compatible platforms give users a great overclocking base to work with. The Pentium 4-1.6A is the current rage for overclocking, due to its 100/400 MHz FSB and lower multiplier, and a very high percentage of these processors can take the 133/533 MHz FSB, that it rivals the old Celeron 300A for overall success rates. That said, both the Pentium 4-1.8A and 2.0A are also growing in popularity, especially among those with a bit more tolerance for risk.
What makes the Northwood version of the Pentium 4 so special for overclockers is both its smaller core and lower voltage requirements. The previous version of the Pentium 4 Willamette core was based on a 0.18 micron process, with only 256K L2 cache and a default voltage of 1.75V. The current Pentium 4 Northwood core is much the same except that it is based on a 0.13 micron process, has 512KB L2 cache, and uses a default voltage of only 1.5V. This doubling of L2 cache is an automatic performance booster, and the .13 micron process and lower default voltage is usually a good indication of serious overclocking headroom.
This potential is given a huge shot in the arm now that Intel has taken the Northwood core backwards as a redo of older models. Along with the new Pentium 4-2.2, 2.26, 2.4/2.4B and 2.53 GHz Northwood models, Intel has also transitioned this newer core to the Pentium 4-1.6A, 1.8A and 2.0A models as well. This is the veritable icing on the overclocking cake, as these lower-speed models seem to be clocked artificially low to fill market requirements of the various OEM and retail markets.