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I have Windows 2008 on VirtualBox on Linux 2.6 on Athlon II X4 630 processor. When installing Windows the number of CPUs was set to 1 (I forgot to change it). Now I want Windows to use 2 processors (cores), so I changed the setting in VB, in Windows Device Manager I see two processors, but Windows Task manager shows performance graph for only one CPU (and I cannot change processor affinity for applications). So how do I upgrade from uniprocessor to multiprocessor? I found this document on MS site, but Windows doesn't find any other computer types besides "Advanced Configuration and Power Interface (ACPI) PC".

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There is a method to change it in 2003 using UpdateUPHal command, not sure it it works for – Moab Feb 26 '11 at 18:34
up vote 2 down vote accepted

Try setting the number of cores in MSconfig>boot>advanced options. You have to reboot the 2008 VM after doing this.

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The "Number of processors" drop down box showed only one option (1 processor). But I selected the "Detect HAL" checkbox and rebooted. Now I have all my cores available and computer type changed to "ACPI x86-based PC". Thanks for the tip. – Tomasz Grobelny Feb 26 '11 at 19:40
the Detect HAL trick worked for me too, thank you both! – Eugenio Miró Oct 27 '12 at 22:21

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