Server CPU's and architecture.

[sao123]

As it seems to me both Xeon and Itanium(1&2) cPU were both designed for servers..
(Well XEON could be in workstations also)

What are their differences? How do they compare? Pin Count, FSB, Bandwidth, Speed, Cache, Other differences?
Both seem to be available in multiCPU systems. when would one be chosen over the other?
What chipsets and motehrboards would you use on each? what Server OS would you run on each?

 

[imgod2u]

If you note the sheer size difference between those and desktop MPU's, that should answer your question. The Itanium 2 Madison 1.5 GHz with 6MB of L3 cache is 421 mm^2. In contrast, the Pentium 4 non-EE is 145 mm^2. There are other differences, such as the FSB. While single-processor targeted desktop MPU's can generally have faster FSB's, server chips usually need to be designed with a more stable and expandable (for 8-way+ configurations) buses.
I'm sure there are plenty of other differences, such as manufacturing technology, transistor and interconnect width and tolerance levels, and most notably, volume production, pricing and yields (you can push a volume-produced desktop MPU to higher clockspeeds vs low-volume server MPU's by the sheer fact that you can sell more speed grades of desktop MPU's).

 

[Jeff7181]

The Itanium is VERY expensive... so... if you're building a server to host MMOG's... or a small web server (by small I mean not Yahoo size)... or a file server for an office... you'd probably go with a Xeon rather than an Itanium. I'm not exactly sure where Itaniums are used most... maybe in more of a specialized field, like an ISP's servers or somethin... I dunno.