Stefan Mileschin

Crucial is playing it safe again with the 5600MHz SKU, by using relaxed timings, but also no less than four pre-loaded profiles, in order to be perfectly compatible with a large range of configurations (entry-level, mainstream or high-end). The modules do barely get warm at the default operating voltage, hence no need for extra cooling and remain about the same if increasing the voltage to about 1.25V, which allows running it at 6000MHz, allowing for extra free performance.

http://www.madshrimps.be/articles/article/1001426/