Review: Intel's New Quad-Core CPUs

Hands-On

The QX9650, the first desktop Penryn chip, is a quad-core CPU that is 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, so the strategy makes sense on several levels. Mainstream users will have to wait until next year for more-affordable 45nm dual-core offerings. At press time, Intel remained tight-lipped about the exact pricing for the chip, but if the $1000-plus prices (as of October 5) of the current top-of-the-line Core 2 Extreme QX6850 and QX6800 are any indication, the new CPU will not be cheap.

Like the existing quad-core crop of Core 2 Extremes, the new product is actually two dual-core CPUs paired on a single silicon package with a shared bus interface, running at 1333 MHz 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 new chip's high transistor count.

Performance

Thanks to some optimizations and enhancements, such as faster divide operations and the larger L2 cache, Intel's own benchmark results from this spring's Developer Forum showed modest performance gains for Penryn over the last 65nm generation of chips running at the same clock speed, as well as moderate power savings.

To see just how much you stand to gain with a Penryn CPU running current hardware and software, we put together a test system built with Asus's Maximus Formula X38-based motherboard, 2GB of DDR2-800 memory, a pair of Seagate ST3320620AS 320GB hard drives in a striped array, and an EVGA GeForce 8800GTS graphics card. We tested both the QX9650 and the older QX6850, using PC World's application-based WorldBench 6 Beta 2.

The QX9650 bested its older sibling by a mere point, 127 to 126. In the majority of our test apps, the new chip was 2 to 5 percent faster, but slower times in Nero and especially WinZip dropped the overall number. Both WorldBench scores would place right in the middle of our top five gaming PC chart, though the GPU and hard-drive setup we used weren't cutting-edge, just close to it. As mentioned earlier, none of the applications in the WorldBench 6 Beta 2 suite are optimized to take advantage of the new SSE4 (Streaming SIMD [Single Instruction, Multiple Data] Extensions 4) instruction set, and only a few WorldBench apps can take advantage of more than two cores.

Intel's own benchmark results released on October 28, as well as the demos we witnessed at the fall Developer Forum, showed much larger performance gains with SSE4-optimized applications, such as an HD-optimized DivX encoder.