The Intel Pentium D 840 ships in a distinctive blue box, differing from the orange colour scheme that has typified recent Pentium 4 processors. The details of the chip are printed on the side of the box as usual. Note that Intel has kindly offered a warning confirming that this chip requires a 945P or 955X based motherboard to work. No mention of nVidia nForce 4 SLI Intel Edition here... surprise, surprise.

The processor we tested was ATX motherboards, as are the majority of dual-core Pentium D's for sale. Intel seems to have put BTX on the back-burner for a little while, which is probably a sensible decision on its part.

The Pentium D 840 itself is practically identical to previous LGA 775 Pentium processors, having the characteristic integrated heat-spreader and flat, gold contact-point covered underside (pinless). The array of resistors and capacitors in the center of the processor's underside remains, and these are as vulnerable to damage as ever, so be careful. The installation procedure is identical to other LGA 775 socket Pentium processors, with the usual warnings about protecting the pins on the motherboard. If you'd like more information about the installation procedure, see PCSTATS guide on the subject.

The heatsink that shipped with the processor is typical, consisting of a large and mostly un-housed fan topping a hunk of copper-cored aluminium extrusion. As we'd expect, the fan was quiet during operation and altogether solid and unremarkable.

Intel Pentium D 840 and Memory Speed

As you probably know, most recent Intel and AMD-based motherboards allow users to alter the speed at which the system memory runs internally. This is separate from the FSB (Frontside Bus) speed used to determine the bandwidth between the processor and the rest of the system in that it affects only the speed of the memory itself.

Decreasing internal memory speed below the default FSB speed can have dire effects on performance, but increasing this value above FSB (for example using DDR2-533 memory at its rated speed with an 800MHz FSB Pentium 4 processor) has historically added little to benchmark scores. From our early benchmarks using the Intel Pentium D 840 though, it looks like that's going to change.

We discovered that if we ran a set of Crucial Ballistix DDR2 memory at 533MHz as opposed to the default 400MHz FSB bus speed of the Pentium D 840/955X Express test system, we gained a significant and noticeable performance increase to the tune of ~5% on most benchmarks. Not bad.

This characteristic of the Pentium D makes sense if you analyze the way the processor works. Both cores essentially compete for FSB and memory time, using the same interface to do work as well as communicate with each other. The Pentium D processors use the exact same 800MHz/400MHz FSB speed that single core Pentium 4 processors do though. Given the increased demand placed on the memory, it's not surprising that increasing its internal speed actually does pay performance dividends.

Early looks then, suggest that buying the fastest DDR-2 memory you can find is a good idea if you plan on investing in a Pentium D processor... so start looking for PC2-8000 or PC2-10000 modules.