If you intend to use the Cryo Cannon to quickly kill swarms, rather than just freezing them, the Ice Storm overclock would be a more suiting choice.

Also, the effect of the EPC's Thin Containment Field's damage can't be boosted by mods or overclocks. It will always deal 240 damage every time you trigger it. You're better off using the Burning Nightmare mod if you're going for max charge shot damage.