The two new official features are:
-New Thermal Interface Material, made with a Next Generation Polymer (NGPTIM)
-Additional capacitors on the underside for smoother power delivery
I will address the latter point first. According to my sources, these are extra decoupling capacitors in order to help smooth the delivery of voltages from the FIVR (fully integrated voltage regulator) to the various parts of the CPU. When at the high end of overclocking, reaching the limits of stability (limited by voltage for a given frequency), this should help maintain a constant voltage especially when load-line calibration settings are fixed. This should have ramifications for home users wanting to overclock significantly (4.7 GHz+) and are on ambient cooling methods, but it would seem that Intel’s main focus would be to assist sub-zero overclockers competing for records.