Xeon (DP) & Xeon MP (64-bit)
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 Intel 64 (formerly EM64T; it is almost identical to AMD64) 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 clock speed during low processor demand. Although it was a bit more competitive than the Nocona had been, independent tests showed that AMD's Opteron still outperformed Irwindale.
64-bit Xeon MPs were introduced in April 2005. The cheaper "Cranford" was an MP version of Nocona, while the more expensive "Potomac" was a Cranford with 8 MB of L3 cache. All these Prescott-derived Xeons have the product code 80546.