For moderate overclock it is fine. I am rolling FX-8120 that is significantly more powerhungry (being mainly 8core procesor and on top of that buldozer varriant) on 4+2 phases overclocked 4ghz (29% overclock from stock 3.1ghz). It can go easy up to 4.2ghz altho my particular chip requires huge jump for such small increase so i just let it be
For safe measures i believe 4.2ghz is pretty safe for FX-6300 and 4.4ghz for FX-4300. Over that i would not go really. Make sure you are not doing it on that 970 MSI mobo sicne it is known for VRM failures even on stock settings. I am rolling with asus m5a97 rev2.0 and it works like char. Friend is also keeping his FX-8320 overclocked at 4.2ghz on same motherboard. So yea its fine for entry level overclocking.