Lewis Curtis from Microsoft forwarded on the tests run by Neal Nelson & Associates comparing AMD Opteron vs. Intel Xeon.
Recent tests by Neal Nelson, an independent computer performance expert, show that while some Quad-Core Intel Xeon based servers delivered up to 14 percent higher throughput, similarly configured Quad-Core AMD Opteron based servers consumed up to 41 percent less power. The test servers used 1 gigabyte memory modules at 4, 8 and 16 gigabyte main memory sizes.
"By themselves the Intel (NASDAQ: INTC) processor chips may use less power, but all current Intel Xeon servers require the use of Fully Buffered memory modules. These FB-memory modules appear to consume more power than the DDR-II memory modules used by the AMD (NYSE: AMD) based servers. The result is that in many cases an Opteron based server actually uses less total power than a Xeon based server." observed Neal Nelson, designer of the test.