Yeah, stock coolers are not ideal for overclocked CPUs. I would suggest going for a nice Noctua Air Cooling or even better a water cooler from either NZXT, Corsair or Cooler Master. Although a good Noctua CPU Fan can provide good results already. Just doesn't look as cool as a water cooler
Also, upgrade your thermal paste to something like a Thermal Grizzly Kryonaut.