Yeah pretty sure it is integrated into the northbridge. Most likely the chip just went bad. You can't replace it, you would have buy a whole new mobo. I would highly recommend getting a new card asap. Using your 9100 could damage your system over time if its really getting as hot as it says.
If you do game, I would recommend 9800GT: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=nvidia+geforce+9800gt&x=0&y=0
A little pricey for a "quick fix", but it will certainly outperform your 9100, especially now that its toasted.