Overclocking the Pentium 4 520 2.8GHz to 3.57GHz

IF YOU’VE BEEN paying attention over the last few months, you’ve no doubt noticed that AMD’s latest Athlon 64s trounce Intel’s newest Pentium 4s almost across the board. That’s a real shame considering that Intel’s 900-series chipsets bring so much to the table, including PCI Express, advanced Serial ATA and RAID features, and high-definition audio. There could be hope for Intel fanboys, though. Since the Pentium 4 500 line stretches from 2.8 to 3.6GHz, lower speed grades may have considerable overclocking headroom just waiting to be exploited.

How much headroom? I got an extra 770MHz out of my Pentium 4 520 2.8GHz, which is quite comfortable running at 3.57GHz with stock air cooling—not bad for a chip that costs less than $160. Could a little help from the overclocking fairy make the Pentium 4 520 2.8GHz a formidable contender against the Athlon 64? Read on to find out.

The overclock
The Pentium 4 520 2.8GHz processor we’ll be overclocking today is an off-the-shelf retail unit that wasn’t cherry-picked or pretested for overclocking potential. I also shied away from using more extreme cooling solutions in favor of Intel’s stock LGA775 cooler. Water cooling, volt-modding, or other more extreme measures may be able to take the processor further, but they’re quite a bit more involved and expensive than our stock setup.


The Pentium 4 520 2.8GHz

Since Intel has gone to great lengths to hinder overclocking with its 900-series chipsets, choosing an appropriate motherboard is essential. In the end, I settled on Abit’s AG8 for several reasons. First, the AG8 offers more tweaking and overclocking options than any other LGA775 motherboard I’ve encountered. The board also supports DDR400 memory, and at only $125, keeps with our budget theme.It also happens that my Pentium 4 520 2.8GHz is perfectly stable on the AG8 with a 255MHz front-side bus, yielding a processor speed of 3.57GHz. Reaching 3.57GHz required a couple of tweaks, though. First, I had to bump the processor voltage up from 1.3375 to 1.4125V. That’s not a big boost, but the system wasn’t stable without it. I also had to swap in memory capable of running on a 255MHz front-side bus. A pair of PC4400 sticks rated to 550MHz DDR did the trick, but with a little extra baggage in the form of more relaxed timings. The PC4400 memory has 2.5-4-4-8 timings, while the PC3200 memory I use at stock speeds runs with tighter 2-2-2-5 timings.

Unfortunately, even fancy high-end memory has problems running with 2-2-2-5 timings on a 255MHz front-side bus, so we’ll have to make do with 2.5-4-4-8 timings while running at 3.57GHz.


3.57GHz with stock air cooling and only 1.41V, not bad at all

Of course, no discussion of overclocking would be complete without the usual disclaimer. Overclocking success can depend as much on the unique characteristics of individual system components as it can on the proper alignment of planets and pure, unadulterated luck. Just because I was able to get my Pentium 4 520 2.8GHz stable at 3.57GHz doesn’t mean that every chip will overclock as high, or that other chips won’t go higher. As always, your mileage may vary.