I am getting a pentium g3258

Solution
It depends on how lucky you are in getting a good chip.
I just got one and can OC to 4.2 using the intel stock cooler at 1.220v.
It is the voltage that is needed at 4.5 that is what matters.
I would suggest setting a safe vcore limit of 1.30 and using whatever clock that will permit. Most likely 4.5 would be there.

Assuming a case with adequate ventilation like two 120mm intake fans, I think a $30 cm hyper212 would do it. If you really want to push, you could use a noctua nh-d15 or Phanteks with dual 140mm fans. But, it seems crazy to spend more for your cooler than the cpu itself.

The problem with even more aggressive coolers like liquid coolers, is that the very high voltages they might permit are not really good for your cpu.
Ha - are you planning to pay more for the cooler than you paid for the CPU? :)

There's no "reliably" in overclocking. All silicon is different. Top-notch overclockers carefully select the best performers from a number of CPUs since the variance can be significant from one piece of silicon to the other.
 
It depends on how lucky you are in getting a good chip.
I just got one and can OC to 4.2 using the intel stock cooler at 1.220v.
It is the voltage that is needed at 4.5 that is what matters.
I would suggest setting a safe vcore limit of 1.30 and using whatever clock that will permit. Most likely 4.5 would be there.

Assuming a case with adequate ventilation like two 120mm intake fans, I think a $30 cm hyper212 would do it. If you really want to push, you could use a noctua nh-d15 or Phanteks with dual 140mm fans. But, it seems crazy to spend more for your cooler than the cpu itself.

The problem with even more aggressive coolers like liquid coolers, is that the very high voltages they might permit are not really good for your cpu.
 
Solution