If you haven't you could download something like Speccy which can provide an oversight of your hardware specs, including motherboard model. At the very least, it could confirm the motherboard model.
From personal experience, I had a pre-built PC which used a Foxconn motherboard. But while the model number matched the one on Foxconn's site, there were several features missing on mine which the one their website had (like additional USB connectors and PCI slot if memory serves).
On an aside, the amount of RAM is limited by the motherboard and the OS. If you're still running Windows XP on the PC, then you're limited to 4 GB of RAM (well... 3.25GB) even if the motherboard is physically capable of more.