The main reason people buy aftermarket coolers is to keep the CPU temperature as low as possible. What made you think you would need an aftermarket cooler? Noise too high on stock? Stock cooler not efficient enough?
I will go a step further and say that there are good reasons not to get an aftermarket cooler.
In particular, the majority of them do not cool the motherboard even a tiny bit whereas the stock coolers do.
If you did want to get an aftermarket cooler (I wouldn't suggest it) you will need to ensure the motherboard components like the voltage regulators still get adequate cooling which might entail an additional expense.
OCing isn't that hard to figure out, especially if your motherboard has UEFI in it.
Anyway, I still wouldn't recommend it, even if you can do it. MSI boards like to blow up when they are OCd with non-stock fans because their voltage regulators get too hot.
What temperatures are you getting now? I don't know off the top of my head avg temps for every processor out there, but I can tell you if the numbers you report are higher than what I would expect. You can measure with HWMonitor from CPUID.