cracking the core is exactly what is sounds like, breaking, chipping, destroying your core. You do this by putting too much pressure onto the core of a chip. It mainly happens in AMD chips but can but rarely in Intel chips. Most of the time cracking occurs through using the wrong hsf on a socket a cpu, or improperly installing a hsf. Other times, a flaw in the hsf design(Globalwin Clip) will crack the core as well. With carefull instilation, you should be able to avoid this.