New Pentiums

The Extreme Edition 955

Naturally, Intel is introducing a new flagship called Pentium Extreme Edition 955 to represent its Presler line. It’s prohibitively expensive, of course (just like AMD’s Athlon 64 FX), and exceptionally warm, all at the same time.

The new Extreme Edition runs at 3.46GHz, matching pace with Intel’s previous single-core champion. It’s the first dual-core chip to leverage a 1,066 MHz front side bus, which should be good news for those concerned about bandwidth considerations on a bus shared by two cores. Theoretical bandwidth jumps from 6.4 GBps to 8.5 GBps, aided by DDR2-667 support rated for up to 10.6 GBps of throughput

The Extreme Edition 955 also carries on with Hyper-Threading, a feature that has quickly become exclusive to Intel’s high-end chips. Not that it matters much—most properly optimized applications seem to demonstrate great gains from two physical cores but very little from the logical cores enabled by Hyper-Threading. Nevertheless, it’s cool to open Windows’ Task Manager and see four concurrent threads.

Familiar extras include the XD (Execute Disable) bit and EM64T technology, both equivalents of features already exposed on AMD processors. EIST (Enhanced Intel SpeedStep Technology) isn’t listed as a component of the Extreme Edition family; however, it is said to come standard on Pentium D chips featuring the Presler enhancements.

Although Intel has seemingly played catch-up on some of those other value-adds, virtualization is one area where the company is laying some foundation of its own. Intel Virtualization Technology lets the Extreme Edition 955 work in concert with compatible software to run multiple operating systems and applications on independent partitions. We set up the latest version of VMware Workstation to give the feature a shot and were able to configure a 32-bit copy of Windows XP Professional along with a 64-bit version. The cool thing about virtualization is that you can switch between the operating systems dynamically without worrying about overwriting boot sectors and so on. Quite the spiffy technology.

Intel isn’t making its Virtualization Technology exclusive to Extreme Edition 955, though. In fact, it isn’t even limiting VT to Presler. Instead, you’ll be able to find it on the other dual-core Pentium Ds along with single-core Pentium 4s. It’ll be one of those pervasive features that Intel wants to spread around.

Heat

Adding cache and extra functionality is all well and good, but it doesn’t come free. The extra transistors (Intel is citing 376 million for Presler) push the Extreme Edition 955’s thermal design power up to 130W. Whether a function of increased thermal density or just a hotter chip, we initially ran into some instability issues that would cause lower benchmark numbers at first, and eventually a series of crashes at various points during testing.

The problem manifested itself every time we applied thermal grease to our reference cooling solution and reseated the heatsink. Apparently, the cooler wasn’t dissipating heat quickly enough on our open-air test bed. Only after attaching an unused reference heatsink with the original thermal pad were we able to get things running smoothly. Three heatsinks later, we’re still wondering why the chip seems to behave somewhat erratically, especially considering that it overclocked very well once firmly covered by a thermal pad.

Presler Redux

The 65nm Presler core powers several other Pentiums as well, all of which will bear the familiar Pentium D moniker. Those will be interesting chips because they’ll be noticeably different from this high-end specimen, shedding the 1,066 MHz bus and Hyper-Threading. Planned frequencies range from 3.4 GHz down to 2.8 GHz at a more conservative 800 MHz bus.

While a larger L2 cache will undoubtedly help the 65nm Pentium Ds outperform existing Smithfield-based offerings, it would have been even better to see the manufacturing advancement usher in some additional frequency or at least carry the accelerated bus speed across a wider range of products. C’est la vie—at least they will all sport lower price tags.