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Heat Dissipation and Power Consumption

Intel positions Core micro-architecture not only as a high-performance solution. Intel considers it highly efficient from the “performance-per-watt” prospective, which we have already seen before in our tests. However, Core 2 Extreme owners and potential buyers are not very much concerned about how economical these CPUs are. Especially, since they boast pretty high typical heat dissipation of 130W as solutions for enthusiasts.

Nevertheless, it seems quite logical to expect 45nm cores and Penryn processors based on them to become more economical. On the other hand, Intel didn’t reduce the TDP for the new Core 2 Extreme QX9650 working at the same clock frequency as the Core 2 Extreme QX6850 on the old 65nm core. So, let’s take a closer look at the heat dissipation and power consumption changes that arrived with the new production technology and new processors.

For our tests we decided to compare the consumed power in identical platforms with different processors – Yorkfield and Kentsfield. During our tests we measured the DC power going through the processor voltage regulator circuitry that would allow us to estimate the processor power consumption without taking into account the efficiency of the onboard processor voltage regulator. During our tests the processors were loaded using Prime95 25.3 utility.

Besides, we have also measured the processor die temperatures to complete the picture. We used CoreTemp 0.95.4 utility to get the readings from the digital thermal sensors built into the CPUs. We used a standard boxed cooler throughout our test session.

We activated Enhanced Intel SpeedStep and Enhanced Halt State (C1E) power-saving technologies during our tests. By the way, Penryn processors drop their clock frequency multiplier to 6x in case of low CPU utilization.

The obtained temperatures and power readings are given in the table below:

As we have expected, the new 45nm production process let Intel reduce the practical heat dissipation and power consumption of the new processors quite noticeably. As we have already said before, new low-k dielectric transistors boast much lower leakage current. As a result, they could get the processor to function stably at lower voltages and currents.

Although Core 2 Extreme QX9650 and Core 2 Extreme QX6850 feature the same typical heat dissipation, in practice Yorkfield consumes about 30% less under maximum workload. In idle state the advantage is even greater: over 50%.

Of course, the power consumption differences affect the CPU temperature as well. Yorkfield processor doesn’t warm up as much as the predecessor, which gives us some hopes for significant overclocking success. So, let’s check it out now.

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