Hardware Reference
In-Depth Information
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
fasterprocessorsrunninga533MHzbus.HTenablesasingleprocessortoruntwothreads
simultaneously, thereby acting as if it were two processors instead of one. For more in-
formation 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 arrange-
ment. 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), al-
lowing 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 Penti-
um 4 Extreme Edition, which is discussed in more detail in the next section. For informa-
tion on the features unique to a specific processor, see the Intel Product Information web-
site at
http://ark.intel.com/Default.aspx
.
Table 3.15 Pentium 4 Processor Information
Forsometimenow,ithasbeenobviousthat“Pentium4”hasbeenfarmoreofabrandthan
a single processor family, leading to endless confusion when evaluating existing systems
for their suitability for a particular task. Because of the three form factors (Socket 423,
Socket 478, and Socket 775) and the range of features available in the Pentium 4 family,
it'sessential that youdetermine exactly whatthefeatures areofaparticular processorina
system if you need to match the system to a particular performance level.
Pentium 4 Extreme Edition
In November 2003, Intel introduced the Extreme Edition of the Pentium 4, which is not-
able for being the first desktop PC processor to incorporate L3 cache. The Extreme Edi-
tion (or Pentium 4EE) is basically a revamped version of the Prestonia core Xeon work-
