Here is a page for troubleshooting audio issues with that board http://www.intel.com/support/motherboards/desktop/sb/CS-020642.htm
Here is the page for support for that board. http://www.intel.com/p/en_US/support/highlights/dsktpboards/d945gcpe
I would check to see if there is something happening with that slot. Try to put another PCI card in the slot to see if it is recognized. If you dont have a card on hand you can pick up a cheap NIC card or wireless card to see if they will work.