Don't break it! You'll damage the CPU/socket. I had the same trouble with my Phenom II X4 980 and its HSF on the same board as you. NO WAY will it latch to the socket on that motherboard. I have assembled many, many AMD systems over the years and that combination was the only one that won't snap into place like it should. I ended up getting this Zalman cooler, and put the stock HSF on the shelf.http://www.newegg.com/Product/Product.aspx?Item=N82E16835118090
There's definetly something wrong with either the bracket that Gigabyte put on that board or the stock HSF latching assembly on that particular size HSF unit.