Can't up broadcom NIC

HI all,

This is my first post on this forum seeking help.   I inherited a pair of  ESXi 5 update 1 on a Cisco C460 M2 servers.  The system comes with 4 on board network interfaces.  Two of them are listed as

     vmnic1     Broadcom NetXtreme II BCM5709 1000Base-T

     vmnic2     Broadcom NetXtreme II BCM5709 1000Base-T

     They are set as vswitch0 and works fine since I see them day 1.

I would like to use the other two interfaces to setup vswitch1 and access another subnet. However, I'm not able to bring up these two interfaces. I tried through the gui to force the speed.  I also tried 'esxcli network nic up vmnic3', but they don't come up.  Are these supported adapters or I'm missing some key steps?

The  interfaces are listed as

     vmnic2     Broadcom NetXtreme II 5711 10Gigabit Etherenet

     vmnic3     Broadcom NetXtreme II 5711 10Gigabit Etherenet

On the switch side, the ports are set the same as all other ports which are also used by a number of servers with the same model and spec but not running ESX.  The ports are enabled and showed as up on the switches.

Any suggestion is welcome.

Thanks

Will