The IBM supercomputing cluster is FAST if you can afford it that is.
Some of the top500 supercomputing clusters use AMD Opterons.
The Opterons beat the Xeons in all benchmarks and their memory bandwidth scales as you add CPUs and memory.
Currently 2 x 940 CPUs with 1 OMC each and 4 stix of PC3200 have 2 TIMES the memory bandwidth = 12.8GB/s
4 x 940 CPUs with 1 OMC each and 8 stix of PC3200 have 4 TIMES the memory bandwidth = 25.6GB/s
8 x 940 CPUs with 1 OMC each and 16 stix of PC3200 have 8 TIMES the memory bandwidth = 51.2GB/s
In the Xeon line memory bandwidth is
1/2 with 2 CPUs
1/4 with 4 CPUs
It doesn't scale at all!
With socket 1207 AMD will be able to easily add Quad Channel RAM or Dual Memory Controllers for Dual-Core CPU's so:
You have 1 PHY CPU
2 cores
2 on board memory controllers
2xDual Channel RAM -- 2 stix / Core -- 4 stix total for TWICE the memory bandwidth!
In a 2way Dual Core SMP Opteron 1207 you would QUADRUPLE your memory bandwidth = 51.2GB/s MAX Theoretical Memory Bandwidth
In a 4way Dual Core SMP Opteron 1207 you would have 8 TIMES the bandwidth = 102.4GB/s MAX Theoretical Memory Bandwidth
in an 8way Dual Core SMP Opteron 1207 you would have 16 TIMES the bandwidth = 204.8GB/s MAX Theoretical Memory Bandwidth
It scales very well.
The Itanium is fast in IA-64 but is terrible in IA-32 -- really terrible because it has to emulate it in software very slow.
The Opterons in 64bit mode are 25-70% faster than any current Intel CPU in 32 or 64bit mode especially in SQL tests ( mysql and postgreSQL ), web server tests ( apache ) and gaming / 3D visualization.
http://www.linuxhardware.org/article.pl?sid=05/02/24/1747228&mode=thread
http://www.anandtech.com/linux/showdoc.aspx?i=2163
http://www.intel.com/performance/desktop/extreme/em64t.htm