Intel Xeon UP/DP (Nocona, Irwindale) processors
Introduction: June 2004 (Nocona), February 2005 (Irwindale)
The Xeon brand refers to many families of Intel's x86 multiprocessing CPUs - for dual-processor (DP) and multi-processor (MP) configuration on a single motherboard targeted at non-consumer markets of server and workstation computers, and also at blade servers and embedded systems. The Xeon brand has been maintained over several generations of x86 and x86-64 processors. Older models added the Xeon moniker to the end of the name of their corresponding desktop processor, but more recent models used the name Xeon on its own. The Xeon CPUs generally have more cache than their desktop counterparts in addition to multiprocessing capabilities. Intel's (non-x86) IA-64 processors are called Itanium, not Xeon.
The Nocona and Irwindale cores
Due to a lack of success with Intel's Itanium and Itanium 2 processors, AMD was able to introduce x86-64, a 64-bit extension to the x86 architecture. Intel followed suit by including EM64T (almost identical) in the 90 nm version of the Pentium 4 ("Prescott"), and a Xeon version codenamed "Nocona" was released in 2004. Released with it were the E7525 (workstation), E7520 and E7320 (both server) chipsets, which added support for PCI Express, DDR-II and Serial ATA. The Xeon was noticeably slower than AMD's Opteron, although it could be faster in situations where Hyper-Threading came into play.
A slightly updated core called "Irwindale" was released in early 2005, with twice the L2 cache of Nocona and able to reduce its clockspeeds during low processor demand. However, independent tests showed that AMD's Opteron still outperformed Irwindale.
All these Prescott-derived Xeons have the product code 80546.
Source: Wikipedia, the free encyclopedia.