Introduction

While Intel’s next-generation 925 and 915 chipsets and the LGA 775 processors that sit on them are barely a few days old, controversy is already brewing surrounding these products. The surprise is the source of the debate – it isn’t the brand new 775-pin socket, whose pins are now located on the motherboard rather than the processor itself (a change which initially had motherboard manufacturers up in arms, as the burden of bent pins between the processor and motherboard now falls on them rather than Intel), rather it’s one topic that’s important to the heart’s of many gamers: overclocking.

Intel has implemented an artificial lock on its latest chipsets which limits CPU overclocking to just 10% over the processor’s stock clock frequency. Once you overclock your processor’s clock beyond 10%, the system shuts off or resets itself. This cycle continues until you reduce your overclock to 10% of the processor’s default frequency.

This has upset many hardware enthusiasts who enjoy dabbling with processor overclocking. Often times you can purchase a slower processor and overclock it to perform similarly or even outpace Intel’s fastest processor offering, or take a flagship chip to unprecedented clock speeds. With just a little knowledge on processor fundamentals and good cooling, you can overclock your processor by 25% or more with just a few keystrokes!

This wouldn’t be the first time Intel has attempted to stifle processor overclocking. In 1998, Intel implemented a locked clock multiplier on its processors for the first time with the 333MHz Pentium II. This was employed to reduce processor remarking, a practice where some unscrupulous vendors will purposely take a system equipped with a slower processor, overclock it, and sell the system as if it were configured with a faster CPU. Even more recently, AMD has integrated a locked multiplier on its own Athlon 64 chips.

But just as a few motherboard manufacturers found ways to implement Intel’s Performance Acceleration Technology in their 865 products, a feature that was supposed to be unique to Intel’s high-end 875 chipset, a select group of motherboard manufacturers have figured out how to get around Intel’s latest clock lock. ABIT, ASUS, Gigabyte, and MSI have all devised ways to get around the lock, and have actually added a few extras beyond just bus speeds to entice their respective boards even further. MSI touts that their 925X Neo Platinum is “Over spec up to FSB1066 support” while ASUS is quick to claim DDR2-600 support in their P5DA line.

In this article we’ll explore the overclocking potential of Intel’s Pentium 4 3.4GHz Extreme Edition, Pentium 4 560 (3.6GHz) and Pentium 4 540 (3.2GHz). The Extreme Edition and Pentium 4 560 are both engineering samples with unlocked clock multipliers, but we decided to leave the multipliers at their default settings in order to simulate a processor you’d buy on the shelf. The Pentium 4 540 is a real bona fide retail processor complete with locked clock multiplier, so it should give you a slight indication of the overclocking potential of these chips, and boy did it overclock, hitting well over 3.8GHz in our testing!

We’ll also take an in-depth look at the 925X motherboards from ABIT, ASUS, and Gigabyte that allow these processors to be clocked to their maximum potential. Along the way we’ll also experiment with DDR2 memory clocked at 600MHz.