The release of the Pentium 4-2.0 GHz is a bit different than previous models, as it introduces a whole new CPU form factor. The previous FC-PGA 423-pin package has now been superceded by the brand-new microPGA 478-pin design. While some aspects of the Pentium 4-2.0 GHz have changed with the transition to microPGA 478, at least for this initial release, much more has remained the same.

While many had conjectured that the move to microPGA 478 would also herald the arrival of the 0.13-micron Pentium 4 die, this has not happened with this release. The Pentium 4-2.0 GHz is still built on the same 0.18-micron Williamette core as found on previous Pentium 4 models and we'll have to wait a bit longer for this highly anticipated 0.13-micron announcement. Another rumor that is making the rounds (mostly due to erroneous info found on the ASUS website) is that the microPGA Pentium 4 processors will up the L2 cache from 256K to 512K. Again, this may be due to someone jumping the gun and confusing the 0.18-micron, microPGA Pentium 4 with the upcoming 0.13-micron version.

Even though the similarities are legion, the microPGA 478-pin CPU package does have a few interesting differences from previous designs, both from physical and architectural points of view.

The major departure is in the physical size of the processor itself. The new 478-pin model is much smaller than the 423-pin version, and in fact, is now almost the exact size of the heat spreader on the current Pentium 4. Gone are the expanses of green PCB space, and this is a move that initially might seem a bit contradictory. After all, how do you add a significant number of CPU pins and still shrink the size of the processor?

A quick peek at the underbelly of the Pentium 4-2.0 GHz tells the tale, as the pins are more densely packed than with the 423-pin version. The technical reasons for increasing the pin count are to accommodate a greater number of power and ground pins to make the jump to 2.0 GHz and beyond, but losing that extra PCB space must also save Intel a few bucks when producing in quantity.

The emergence of the microPGA 478 architecture seems to be something if a "re-do" of the entire Pentium 4 line. In addition to the reviewed Pentium 4-2.0 GHz, Intel will be moving down the CPU ladder and re-releasing the Pentium 4 in the microPGA processor package at speeds as low as 1.4 GHz. For those currently using a current FC-PGA 423-based system, don't despair, as Intel will also release a 2.0 GHz Pentium 4 for that platform as well. Above 2.0 GHz will firmly be in microPGA 478 territory and no further speed increases are expected for the Pentium 4 423-pin processor line.

We do admit to being a bit surprised that a die shrink did not accompany the new Pentium 4 processor package. It's almost as if Intel had determined that the 478-pin design was the right way to go for the Pentium 4 but for whatever reason, could not fit the spec into the initial run of the Pentium 4. The roadmap for the Pentium 4 has long been in excess of 2.0 GHz and Intel had to know that the FC-PGA 423-pin package couldn't handle the requirements of these higher-speed Pentium 4 processors. That said, we can only hope that Intel achieves some level of consistency with their new microPGA 478 processors and that it remains a viable and highly upgradeable platform for some time.