Windows 2K and SQL 2K do not understand hyperthreadind. To them it looks like extra CPUs exist, and since Std has a 4 CPU limit, that is why you cannot hyperthread.

We recently moved from a single here (at SQL Server Central.com) to a dual hyperthreading machine and it runs great, but it runs the web server as well and we didn't do great benchmarking. It was a HUGE uprgade, so hard to say. At work, informally, I heard some of the JD Edwards benchmarks were slower with hyperthreading enabled for dedicated SQL machines. Can't verify that.

This paper mentions SQL 7 isn't supporting this (http://www.microsoft.com/sql/howtobuy/SQLonHTT.doc)

Mentions perf issues:http://www.sqlmag.com/Forums/messageview.cfm?catid=5&threadid=14696

Steve Jones

sjones@sqlservercentral.com

http://qa.sqlservercentral.com/columnists/sjones

http://www.dkranch.net