I just put together a new Xeon E3-1276 v3 (Haswell) board (like the i7-4790 with more cache and ECC memory capability). With the supplied cooler, even with no case, it overheated (100 degrees Celsius! ) after one minute running Prime95 64-bit. (NOT overclocking, BTW)
Even a simple closed-loop liquid cooler essentially moves the bulky radiator outside and removes the size and weight restrictions for motherboard mointing and fitting inside a case with airflow.
I've never had a leak once a system is tested and comissioned, since I turned to water cooling in the Pentium Prescott era.
For mundane systems I use something like the Coolermaster big square radiator that sits on top of the CPU with a 140mm fan on the side. But for sustained performance cooling, you would also need (at least) case fans or ducting to go with that, and I don't know just how much it could handle without being very noisy and take a huge volume of air.
From the discussions in the comments, it appears that performant code can push it far beyond the thermal limits, so water cooling is necessary to make use of that performance capability.
To make it clear: this is not overclocking and is running the MB, memory, and CPU at stock specifications. Number crunching code can significanly exceed what the supplied stock cooler can handle.
Likewise, the turbo core feature is not applicable because (with the standard settings) it will not be engaged unless some of the cores are idle, and simply not boosting will not be considered an error if boosting would push it over the limit.
An after-market heat sink that maxes out the weight that can safely be supported by the motherboard could handle more heat if you give it enough air flow, but I can't say for certain what that is capable of with in-case use. My gut feeling is that if it doesn't make as much noise as a vacuum cleaner, it won't keep up.
Considerations: some similar processors have fewer cores or lower clock speed, and that would make a difference.
I also have a E3-1245v3 (3.4GHz instead of 3.6) running a file server and it has no problems whatsoever with a 5" square heat sink. The emphatic yes to liquid cooling is for High Performance Computing (CPU number crunching) usage.
Also, if testing the effectiveness with your actual use case, be careful not to under-do it. The software might get updated to use new instructions or be optimized for that architecture, and you would not be able to take advantage of the performance improvements, if that now pushed you 20W beyond your thermal limit.