ThinkComputers.org posted a guide about how to find out the model of the motherboard you have
Knowing who makes your motherboard and what model you have is very important. Many motherboards have new drivers and BIOS updates that fix problems with the motherboard once it has been released. To download and install these updates you need to know the exact model name and manufacturer of your motherboard. Many people who have built their own computer should already know this, but if you somehow forget or you have purchased your computer from a store this guide will easy show you where to find this information.How to find out the Model of the Motherboard You Have
