There are numerous methods you can use to obtain the motherboard manufacturer and SBIOS information. Here are some examples:
1) When your system boots up during P.O.S.T (Power On Self Test), this information can be obtained from the monitor screen. On some PCs, you'll probably see the manufacturer's company logo so you may want to consider downloading a program to retrieve it.
2) Download a freeware that gathers information from your system which you can run inside your Windows OS. Here's a utility that will do just that:
After the program launches, click on the Mainboard tab. From this page you should be able to obtain the manufacturer, motherboard model, SBIOS and motherboard related information.