Power Consumption and Heat Dissipation

As we have already mentioned above, one of the key features of the new core stepping should be the reduced heat dissipation and power consumption. Of course, we need to double-check this. For the corresponding experiments we decided to compare the power consumption of the new Pentium Extreme Edition 965 against the power consumption of the older Pentium Extreme Edition 955 processor based on the B1 core stepping. In order to obtain correct results that could later be used for fair comparison, we overclocked Pentium Extreme Edition 955 up to 3.73GHz by raising its clock frequency multiplier. The Vcore remained unchanged in this case. This approach allowed us to compare the power consumption (and heat dissipation) of two Presler processors with different core steppings working in identical conditions. Note that Pentium Extreme Edition 965 processor worked with the Enhanced Intel SpeedStep Technology disabled.

As always, we used a special S&M utility to measure the maximum power consumption (you can download this utility here ). We measured the current that goes through the CPU power circuitry. So, the numbers given below do not take into account the efficiency of the CPU voltage regulator laid out on the mainboard.

Here are the results:

These numbers are quite logical. Intel promised to reduce heat dissipation in the new core stepping and they did. Thus, Presler has become about 18% more economical in Burn mode, and got the power consumption reduced by about 30% in Idle mode when Enhanced HALT State technology kicks in. However, even though C1 core stepping has become much more economical, Intel’s dual-core processors will still not be able to compete against AMD’s rivals here. The maximum heat dissipation of the dual-core AMD Athlon 64 X2 processors doesn’t exceed 100W, which remains an unattainable bar for Presler.

In addition to the picture we have just described, I would like to mention the processor temperature measurements taken with the regular boxed cooling installed:

Well, I don’t think any comments are necessary here. You can clearly see that the boxed cooler can hardly cope with cooling down the older Presler revision overclocked to 3.73GHz. As for the Presler C1 core stepping, things look a way better here…