SQL Server vCPU and Scheduler

Here is my config:

1. ESXi 4.1

4 sockets, 6 cores per sockets.

2. VM: Windows 2008 , SQL 2008 R2 standard 32bits.

assigned 6 vcpu

Inside sql, I can see it has 6 logical cpu. however only 4 SCHEDULER can be used (if somebody also database admin of mssql will understand what i mean).

are there any config missed on ESXi side cause MSSQL can use all 6 logical CPUs for MSSQL schedulers??