The -iqnumbercpus switch on the Sybase IQ startup command lets you specify the number of CPUs available to IQ. It overrides the physical number of CPUs for resource planning purposes. The value of the parameter defaults to the total number of CPUs, but the range of available values is 1 through 512.
Sybase recommends using -iqnumbercpus only in the following situations:
On machines with Intel® CPUs and hyperthreading enabled, setting -iqnumbercpus to the number of CPUs available
On machines where an operating system utility has been used to restrict Sybase IQ to a subset of the CPUs within the machine
Setting -iqnumbercpus higher than the number of available CPUs may affect performance.