As above, that will vary by how lucky you get in the silicon lottery. It's best to think in terms of how much voltage the cooler can handle. The higher the OC, the higher the voltage required. I use this as a starting point for the **average** PC
Up to 1.200v = Very Good Air Cooler (Hyper 212)
Up to 1.250v = Best Air Coolers (Phanteks PH-TC14-PE, Silver Arrow or Noctua DH14) ....... Dual 140mm CLC / AIO Cooler w/ 1500 rpm fans (Corsair H110)
Up to 1.275v = Extreme Speed Dual Fan CLC / AIO w/ 2700 rpm fans (too noisy for most folks)
Up to 1.287v = Best air coolers (Cryorig R1 / Noctua DH-15)
Up to 1.300v = Swiftech AIOs ( Swiftech H220-X / H240-X)
Up to 1.325v = Custom Loop w/ 15C Delta T (3 x 120mm / 140mm) *
Up to 1.400 = Custom Loop w/ 10C Delta T (5 x 140mm or 6 x 120mm) *
* At this level having the GPU(s) also under water is assumed
If you live in a moderate climate, room is temperature controlled or you have more than basic case cooling, you can go higher.