4GHz seems to be the upper limit on air cooling. I've said before that overclocking via the Bus and not the Multiplier will yield the best performance. The CPU at 4GHz and the NB at 2GHz will perform worse than the CPU at 3.5GHz and NB at 2.5GHz.
So a good motherboard will be needed, yours should be more than enough to overclock the CPU to a decent speed.
I'd recommend getting a 1600MHz kit of RAM as well. Unless you use all 16GB you have, it won't increase your performance and will put more stress on the CPU, meaning you'll need higher voltages, which is bad for cooling performance and CPU longevity.
You'll need a good application to stress the CPU and monitor temperatures. I would suggest Intel Burn Test for stress testing. And HWMonitor for temperature monitoring.
You're going to need a better cooler than the stock one too. How much would you be willing to spend on a Cooler (and accessories like fans and thermal paste?)
Hmmm, Ill be going to Gskill ripjaw 1866 16gb pretty soon.. I have like 6 fans total in my case, and one directly on the CPU. Is there a dummies guide to overclocking via the bus?