Try this:
- Right click on My Computer.
- Click Properties.
- Go to Device Manager and expand Universal Serial Bus.
- Locate Intel(R) 6 series/c200 series Family USB enhanced Host controller.
- Right click on it and then select Properties.
- Click on Details tab; select Hardware ID from the Property drop down menu.
If Hardware ID ends in 04, the system is using B2.
If Hardware ID ends in 05, the system is using B3.