Date:
Sunday , July 18, 2004
Author:
Kyle Bennett
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Overclocking the 2.8GHz LGA775 Pentium 4

Not only does this give a enthusiast view of what power is tucked into the new Pentium 4, it gives us an idea at what the upcoming Intel 1066MHz bus speed will bring. Our testing also provides information cutting edge enthusiasts want to know about DDR2 RAM and PCI-Express video card power needs.

Introduction

The folks over at NewEgg were kind enough to help us get hold of one of the first 2.8GHz LGA775 Pentium 4s that have slipped into retail. This is the retail boxed CPU and not the OEM version that we so often see. Also you will note that this CPU carries Intel's new numbering scheme. Our 2.8GHz CPU now officially carries a processor number of "520." To learn more about the logic behind their processor numbers, you can get all the information here directly from Intel.

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As you can see from the packaging above, this is a "SL7J5" specification Pentium 4. A trip over to Intel's spec finder pages will net you the following information.

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Most enthusiasts will immediately note the Thermal Spec and Core Voltage numbers. Our CPU is specified to work up to over 150°F and up to 1.4v Vcore. The 90nm shows that this is of course a "Prescott" core CPU using the 90nm process, and as all retail Intel CPUs is multiplier locked. Our 2.8GHz part is locked at "14." 14 X 200MHz = 2.8GHz.

The 2.8/520 LGA775 CPU

As you are likely aware, the newest Land Grid Array or LGA processor packaging format is one of the most drastic changes we have seen in desktop processors since slotted CPUs left us a few years ago.

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Gone are the pins from the CPU as they now reside on the motherboard. The rest of the Pentium 4 remains pretty much unchanged from immediate former iterations.

Overclocking Intel CPUs

Intel and AMD CPUs differ a bit in the approaches you can take when overclocking them. Unlike AMD processors, Intel's are "multiplier-locked" or "hard-locked". What this means is that the enthusiast cannot simply change the multiplier to overclock the CPU like we did in the old days when overclocking was still a black art. No longer can you change the integer in the equation, like changing 14 X 200MHz to 16 X 200MHz in the motherboard BIOS. Intel initiated multiplier locks on their CPUs due to the fact that many CPUs were showing up on the gray market with their multipliers changed and being sold for faster CPUs than Intel labeled them. This of course impacted the enthusiast as well.

Now days we are limited to pushing forward the Front Side Bus, or FSB, in order to wring every last bit of performance out of our CPUs. So today, we will be turning our equation from 14 X 200MHz to 14 X 250MHz, in order to get high clock speeds.

New enthusiasts do need to be aware though, that many operations on the motherboard are associated with or are functions of the FSB. So as the FSB scales, so does the memory bus, PCI-Express bus, and/or AGP and HyperTransport busses depending on whose technology you are using. Overclocking with the wrong motherboard will leave you pulling up short, so picking the right motherboard and CPU are very important.

Intel Overclocking Protection

The new Intel 925X and 915 series of chipsets have been rumored to have some sort of "overclocking protection" and this has been verified with Taiwan. Many of the rumors of how this is being done are a bit misleading though. The new chipsets quite simply look for a CPU that is not running at its specified clock speed when the motherboard boots. If the boot process identifies an overclocked CPU, the system stops the boot process. Suffice it to say that we have yet to see a 925/915 motherboard with this protection active and we doubt that we will see such a board from the "Big 5" motherboard makers, as they will likely find ways around Intel's overclocking protection. That said, we have only seen 925/915 motherboards from ASUS and ABIT as of writing this.