Your motherboard is based on the AMD 770 chipset and supports processors up to 95W TDP. So technically your motherboard will support Athlon II processors, providing the TDP is <= 95W. One of my friends is using it with Athlon II 630, and it is working fine.
But initially after you install the processor, probably it will show unrecognized processor, if the latest bios is not updated. After the latest BIOS installation, it will detect the processor properly. I would suggest you to update the BIOS to latest one using your existing processor. You can use the ASUS software provided to upgrade it. Then plug the new processor.
It is not a gaming mobo, but the performance will be decent, if a good Gfx card is provided.