The Pentium D is something of a stepping stone in the world of CPUs: both a throwback to the days of gigahertz races and high TDPs, as well as the trailblazer that brought a new era of dual-core computing to the desktop PC.

The first Smithfield models – the 800 series – have 1MB of Level 2 cache for each core and operate with a front side bus speed of 800MHz. They support XD-bit security and EM64T extensions, while the 830 and 840 models also offer EIST for power saving. Released later, the bottom-end 805 processor sports a lower 533MHz front side bus and is the budget model.

Gradually introduced throughout 2006, the Presler 900 series improved the Pentium D. These sport 2MB of Level 2 cache for each core and are produced using the more efficient 65nm process rather than the 90nm of the 800 series.

There are two distinctions in this range: the 9x0 models support VT (virtualisation technology), while the cheaper 9x5 models lack this feature (so the 920 becomes the 915 and doesn’t have virtualisation). With significant savings on offer, you should choose a 9x5 CPU if you don’t need VT.

Value for money
The Pentium D family is stuck between a rock and a hard place, due in part to the introduction of the Core 2 Duo and also declining availability. You’ll need to pay $260 for the privilege of virtualisation on a Pentium D and the 940 was the only compatible model we could find that was still available. If you want a CPU with VT, you should look to the Core 2 Duo range.

At $95, the 915 represents a decent deal and is undoubtedly the cheapest way to give your Intel-based PC dual-core power. It will also tempt anyone considering buying a top-end Celeron D. The $138 935 is also a decent choice, scoring exactly 1 – the same as the dearer 940 which is the model every processor on test is compared against - providing performance comparable to a low end Core 2 Duo. If you’re not locked into Intel, however, an Athlon X2 3800+ also costs $95 but is 5% faster than a Pentium D 935.

If the price didn't put you off the 8XX Pentium D's, also consider that they have less L2 cache than their more powerful and less expensive brethren.

Ultimately, the 915 and 935 are affordable ways to upgrade to dual core and are better choices than the dearest single-core Celerons. The 935 costs $138, which is the most you should be considering spending on a Pentium D, as past this point you’re into Core 2 Duo territory.


Pentium EE
The Extreme Editions aren’t simply standard Pentium Ds with unlocked multipliers, although that’s their biggest attraction. They are hard to find and not worth investigating, but if you do happen to stumble across them it's good to know how they differ from the standard Pentium Ds.

The 955 and 965 both operate with a front side bus speed of 1066MT/s, rather than the usual 800MT/s. It means the multipliers are lower – and frequencies higher – than those of their standard Pentium D brethren, making them good overclockers. The 955 and 965 also support Hyper-Threading at the expense of SpeedStep technology.

But the usual drawbacks apply. Prices are generally extortionate, and the performance increase over (only the slowest) Core 2 Duos is nowhere near enough to justify the prices.