Profit & environment
1) When process yields are low, nobody minds that chips with defective cores or cache are sold as lower end models. A Phenom X4 sells for 100% over cost, and Athlon X2 might only sell for 15% over cost.
2) When process yields are high, every chip could be made into a Phenom X4 but there is still demand for Athlon X2 for use in low-end systems. System builders won't pay and don't need so much power, so some chips are made into Athlon X2s, so that AMD can sell more chips and make more overall profit.
3) To prevent remarking and other arbitrage, the disabling mechanism is a combination of shorting some fuses (permanent damage.) In addition, a code on the CPU instructs the BIOS which cores on the CPU are usable.
4) Intel has developed a software-based system that can make a static change to the CPU's configuration. "The upgrade enables changes to the firmware (driven by the Intel® Active Management Technology Management Engine in the chipset) that in turn modify the hardware."
The actual mechanism is not described but I would guess that the chipset is shorting some fuses on the CPU to *enable* the cache and hyperthreading.
This means that it is no longer necessary for the CPU manufacturers to permanently limit a CPU for marketing reasons. It's the same business model, just with more flexibility.
5) This is a positive change. It's better for the environment. If we can upgrade our CPUs there will be fewer CPUs created. If a consumer doesn't want to give Intel the full profit margin upfront, the consumer can pay later for it.
6) If people hate the idea of buying CPUs with locked features, they are not obligated to do so. I recently even paid about $10 extra to buy a Phenom X2 965 with no multiplier locks. But I do have an i7 920 with a locked multiplier, and a Pentium D 905 with locked hyperthreading, and a Celeron D with a locked cache. I got what I paid for. However, I wish this tweak of the business model had arrived earlier so I could unlock my other CPUs.
