Intel Designed its Forthcoming Xeon for Easier Recycling

If multiplying the number of cores per CPU allows performance gains at a rather low cost, it has one disadvantage during their production. If one core is defect, the entire CPU is discarded and trashed, making the price of multiple core CPU rather expensive as multiple core engraving is experiencing higher failure rate than single or dual core CPU.
Such problem might increase in the near future with the release by the end of the year of Octo Core Xeon, so Intel designed a way to inactivate specifically some cores while still selling the CPU with defective cores.

Instead of trashing such CPU, Intel will just inactivate definitely defective cores and sell the CPU as a 6 core unit or an Octo Core CPU with less cache. According to Intel this process will not impact performance or power consumption of the CPU.
AMD is already using such technology for Phenom CPU (usually quad core), available as three core unit when one core is inactivated.