The first full-scale unveiling of Intel's 64-bit technology on the desktop level is the new '6xx' line of Pentium 4 processors, along with the new 3.73GHz Extreme Edition chip. All of these Socket 775 processors contain the EM64T extensions as well as a couple of other major new hardware changes.

The 6xx chip line includes the 630, 640, 650 and 660 at speeds of 3.0GHz, 3.2GHz, 3.4GHz and 3.6GHz respectively. All these processors use an 800 MHz bus paired with DDR or DDR2 memory. A 3.8GHz version should appear in the next three to four months also.

More notably, all of the chips in the 6xx line, as well as the 3.73GHz P4 EE feature a massive 2MB of Level 2 cache memory. This is double the largest amount found on previous Pentium 4s, bringing these new chips into territory previously reserved for the outrageously expensive EE (Extreme Edition) Pentium 4 chips and the newer Xeons.

The new 3.73GHz Extreme Edition processor gets a bump up to the shiny new 1066MHz bus to compensate for this loss of cache superiority; gotta keep those product lines separate after all... It looks like there will be very little point in investing in an EE P4 until Intel adds some more performance features to the line, considering that these chips hold an almost 30% price premium over even the new Pentium 4 660 processor.

The extra cache memory should assist in some applications, most notably 3D rendering and database and content creation applications. It will also introduce more latency which may be slightly counter productive in certain situations.

Currently, a mere BIOS update should be all that's needed to update any Intel Socket 775 board to work with EM64T enabled chips. Intel has stated that they intend to enable the technology across their Pentium 4 and Celeron processor lines by the end of the year.

EM64T will also eliminate the current 4GB memory addressing limit placed on 32-bit processors, though this will need a new generation of chipsets from Intel to be implemented before we see any manifestation of this on the desktop. Still it does for Intel servers what the AMD64 extensions and the Opteron did for AMD; allow more memory in servers without performance reducing add-ons.

The battle lines between Intel and AMD for the future of the desktop and server markets are now more sharply drawn. On one hand, AMD currently has a more efficient interconnect system (on-die memory controller, Hypertransport) with less bottlenecks, and still maintains a stranglehold on the performance gaming crown. They also have the respect that goes with a proven 64-bit product that has been accepted on all levels of the marketplace.

On the other hand, Intel's new chips have massively larger amounts of cache memory, which could translate to some serious performance advantages in certain facets of business computing. Also Intel deserves some kudos in our mind for sticking with Socket 775 for 64-bit chips (for now at least). The new 64-bit capable chips keep the other advantages of the Prescott P4 architecture too, including Hyperthreading capability and native SSE3 support.