Hardware Reference
In-Depth Information
instructions if they are not optimized for this processor. Another important architectural advantage is
HT Technology, which can be found in all Pentium 4 2.4GHz and faster processors running an
800MHz bus and all 3.06GHz and faster processors running a 533MHz bus. HT enables a single
processor to run two threads simultaneously, thereby acting as if it were two processors instead of
one. For more information on HT Technology, see the section “
HT Technology
,
” earlier in this
chapter.
The Pentium 4 initially used Socket 423, which has 423 pins in a 39×39 SPGA arrangement. Later
versions used Socket 478; the final versions use Socket T (LGA775), which has additional pins to
support new features such as EM64T (64-bit extensions), Execute Disable Bit (protection against
buffer overflow attacks), Intel Virtualization Technology, and other advanced features. The Celeron
was never designed to work in Socket 423, but Celeron and Celeron D versions are available for
Socket 478 and Socket T (LGA775), allowing for lower-cost systems compatible with the Pentium 4.
Voltage selection is made via an automatic voltage regulator module installed on the motherboard and
wired to the socket.
Table 3.15
includes a guide to Pentium 4 processor features as well as those for the Pentium 4
Extreme Edition, which is discussed in more detail in the next section. For information on the features
unique to a specific processor, see the Intel Product Information website at
Table 3.15. Pentium 4 Processor Information
Pentium 4 Extreme Edition
In November 2003, Intel introduced the Extreme Edition of the Pentium 4, which is notable for being
the first desktop PC processor to incorporate L3 cache. The Extreme Edition (or Pentium 4EE) is
basically a revamped version of the Prestonia core Xeon workstation/server processor, which has
used L3 cache since November 2002. The Pentium 4EE has 512KB of L2 cache and 2MB of L3
cache, which increases the transistor count to 178 million transistors and makes the die significantly
larger than the standard Pentium 4. Because of the large die based on the 130-nanometer process, this
chip was expensive to produce, and the extremely high selling price reflects that. The Extreme
Edition was targeted toward the gaming market, where people are willing to spend extra money for
additional performance. The additional cache doesn't help standard business applications as well as
it helps power-hungry 3D games.
In 2004, revised versions of the Pentium 4 Extreme Edition were introduced. These processors are
based on the 90-nanometer (0.09-micron) Pentium 4 Prescott core but with a larger 2MB L2 cache in
place of the 512KB L2 cache design used by the standard Prescott-core Pentium 4. Pentium 4 Extreme
Edition processors based on the Prescott core do not have L3 cache.
The Pentium 4 Extreme Edition was produced in both Socket 478 and Socket T form factors, with
