System information only shows the motherboard manufacturer, not the model number of the motherboard. At least on my configuration with Windows 8.1.
Rather than downloading yet another tool to take up space and potentially never be used for anything else, I'd personally recommend finding out the manufacturer through the System Information, and then downloading the firmware updater from the manufacturers website.
This will accomplish two goals:
1) Tell you the exact model number of your motherboard
2) Let you upgrade your firmware to the latest version, which is something everyone should do once or twice a year (unless you are using an old or non-standard operating system).