There's a new high-end desktop chip in town - namely, the Intel QX9650, the first from Intel's new Penryn family of CPUs.

The Intel QX9650 is a quad-core CPU that's aimed squarely at enthusiasts and other early adopters. (Among other things, it has no locks to prevent users from overclocking it.) For the most part, only select games and high-end audio or video applications can take advantage of more than two cores.

Prices were unavailable at the time of writing, but since its predecessor, the Intel QX6850, still costs around £650, you shouldn't expect the Intel QX9650 to be cheap – mainstream users will have to wait until at least next year for more-affordable quad-core offerings.

What's really major about Penryn is that these are the first processors built on a manufacturing process that shrinks each chip down to a mere 45nm (nanometers - or about 1/18000 the width of a human hair). That's down from the 65nm process Intel has used for its current Core line and the 90nm process it used on some Pentium 4 chips. The company has already demonstrated a 32nm process that it intends to begin using to produce chips in two years.

By shrinking the size of the transistors in its chips, Intel can produce more CPUs from the same amount of silicon, or build more complex chips in the same amount of space. For example: a Celeron 300 made in 1995 using a 250nm process measured 131mm2, yet contained a mere 7.5 million transistors; a current 65nm Core 2 Duo is a scant 11mm2 larger but contains 291 million transistors; and the new 45nm, quad-core Core 2 Extreme Intel QX9650 that we tested for this article measures 214mm2 but contains a whopping 820 million transistors. The upshot of this is that the 45nm process should allow Intel to keep churning out superfast desktop chips for the foreseeable future.

Like the existing quad-core crop of Core 2 Extremes, the new Intel QX9650 is actually two dual-core CPUs paired on a single silicon package with a shared bus interface, running at 1333MHz in this case. Each of the two dual-core CPUs carries a shared 6MB of secondary (L2) cache, up from the 4MB of each core of the previous QX6850 chip, for a total of 12MB. This larger secondary cache is partly responsible for the Intel QX9650's high transistor count.

Although they use the same LGA 775 socket as all recent Intel desktop processors, Penryn chips aren't necessarily a drop-in replacement. Intel is only guaranteeing reliable operation with its P35 and X38 chip sets, not with those of the older 975X and 965 families. Motherboard vendors such as Gigabyte, however, are working to expand that support.

Intel is pushing DDR3 as a preferred memory companion for its 45nm CPUs, and has incorporated support for it (as well as DDR2) into its more recent chipsets. But given the high cost and small performance benefits of DDR3, many motherboard manufacturers are still designing their X38 motherboards around DDR2. Even the high-end Asus Maximus board we used for testing uses DDR2.

Bearing in mind the type of components that are likely to be used with the Intel QX9650 today, assessing the exact performance isn't easy. We put together a test-bed that included 2GB of PC2-6400 (DDR2-800) memory, two 320GB Seagate hard drives in a striped array, and an EVGA GeForce 8800 GTS graphics card, and found that the Intel QX9650 outscored the older (but still very high-end) QX6850 by just one point in our WorldBench tests. In the majority of test applications, theIntel QX9650 was between 2 and 5 percent faster, but slower times in Nero and WinZip dropped the overall score.

However, it's important to note that amongst the features Intel is touting are the new SSE4 instructions. These can supposedly greatly speed up such tasks as video encoding. Intel has itself shown off some impressive scores that show it faring well in, for example, an HD-optimised DivX encoder. The lack of available SSE4 applications makes it difficult to say how strong this chip will be in the long run. But certainly, on today's mainstream applications, the performance increase is only modest.


For the moment, most users would gain little advantage in upgrading to a Penryn CPU - the chip may not be compatible with your PC's motherboard, the market has few SSE4-optimised applications that would allow it to shine performance-wise, and it will certainly be extremely expensive. And rumours have hinted at imminent new chipsets that may offer superior support for the new processor line. So unless you simply must live on the bleeding edge, wait a few months to see how the market shapes up and simply stand back and admire the Intel QX9650.