Did you get a CD with the mobo? If so, a good enough start will be on there. If we are going to find it for you, the motherboard model would be useful. The first thing one of us would do is go to the mobo maker's site, go to Support, and enter the model number.
If your machine is a Dell, try here: http://www.dell.com/support/drivers/us/en/04/DriverDetails/Product/optiplex-210l?driverId=R126541&osCode=WW1&fileId=2731114385
You could go to this page: http://downloadcenter.intel.com/SearchResult.aspx?lang=eng
and enter the model string above in the search box. Good luck!