Higher Thermal Power Loss Of Up To 130 Watts, Continued

The following tables list the thermal dissipation classes for the various CPU series. Note that the dual core series have a higher TDP of up to 130 watts, despite using the same PRB number.

In an effort to reduce costs, a number of motherboard manufacturers designed boards that only support the VRM Spec 9.1. These boards are unable to supply enough current for CPUs that belong to a higher performance requirement category.

Beware: Some less expensive motherboards are only equipped for platform compatibility 04A. Manufacturers state the compatibility level in their products' technical specification. In this example, both 04A and 04B are supported.

Intel introduced the Performance Requirement Bit (PRB) to protect the voltage regulation modules on motherboards from overstress as a result of inserting a CPU from a higher performance class into the socket. The PRB is defined in the VRD (Voltage Regulator Down) specification that Intel developed for this specific case.

The VRD Spec was primarily defined to protect the voltage regulation modules on motherboards.

This is what VRD is supposed to prevent: The fixed voltage regulators on this board died a smoky death from overheating.

With the help of a circuit defined in the VRD spec, the Performance-Bit (ForcePR#) can be set if the fixed voltage regulators overheat during operation. This forces the CPU to switch to a multiplier of 14x, reducing energy consumption. Simultaneously, the core voltage is lowered through the fixed voltage regulators.

Intel provides an example of how motherboard manufacturers can implement the protection circuit (Force PR#) on their boards.