Yes, it's possible the OC it, but you might be limited on the mobo's ability to do so just because it's mATX, so it won't have as much options in the BIOS like the mobos designed to OC.
Depends on your mobo, but my guess is, you won't get much out of it. Even with a good mobo, the Athlon X2s don't overclock a ton (except some of the BEs) and especially not on a stock cooler, which can barely handle the smallest voltage increase.