We need to disable hyperthreading on several MacPros.
We have just two types of Macs - Dual QuadCore 2.4 "Westmere" and single CPU SixCore 3.66 "Westmere". All machines run 10.6.8
For some strange reason the terminal command "sudo nvram SMT=0" works just fine on some dual-CPU machines and does not on others including all single-CPU machines. While checking NVRAM state all machines show this flag as set correctly, but some of them still show doubled number of cores in Activity Monitor.
All other means of disabling hyperthreading (Processor.prefpane, hwprefs, CHUD tools) have no effect at all.
I would greatly appreciate any clue on the issue.