I've two machines with SQL Server 2012 Express SP1 with default configuration settings for CPU usage.
I'm using this query on my work machine:
SELECT cpu_count FROM sys.dm_os_sys_info
It returns "4", which is true.
The same query on production machine returns "1" (that machine has 4 processors too). There's no additional CPU usage settings in both cases, except defaults.
Production machine is a virtual machine, which, possibly, was reconfigured after SQL Server installation.
Is there any way to reconfigure SQL Server for using of 4 processors?