It doesn't appear to be compatible.
Support for AM3/AM2+/AM2 processors: AMD Phenom™ II processor/AMD Phenom™ processor /AMD Athlon™ II processor/AMD Athlon™ processor/AMD Sempron™ processor
* If you install AMD AM3/ AM2+ CPU on AM2 motherboard, the system bus speed will downgrade from HT3.0 (5200MT/s) to HT1.0 (2000 MT/s) spec; however, the frequency of AM3/ AM2+ CPU will not be impacted. Please refer "CPU Support List" for more information.
check this link
http://www.gigabyte.com/products/product-page.aspx?pid=3490#sp