Cooling down the current generation of high performance processors is more of a challenge as die sizes drop packing more and more transistors into an ever smaller package. Cooling them down is much easier when running at stock speeds, as you might have guessed, as even the box solution can handle the thermal load, barely. Adding additional voltage and upping the clock speed effectively renders the box solution obsolete with even small bumps in voltage and/or clock speed. An improved air cooling solution such as those from Noctua and Phanteks help control the thermals but still have a hard time pushing higher, bringing rise to the need for something better.