Desktop CPU Power Survey, April 2006

CPUs|Motherboards | Power
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This article has been an exhausting exercise, despite it being still not an exhaustive sampling of current processors for desktop use. Nevertheless, most of the major processor families from Intel and AMD were covered.

Our focus on thermals, power and energy efficiency led to mostly predictable results: Mobile processors are best, followed by AMD desktop processor in general, and then Intel desktop processors. The power efficiency of AMD Athlon 64 single and dual core processors is excellent, even for their highest performance models. The Intel desktop processors suffer from inefficiency, even on the 65nm die. We are not sorry that the upcoming Intel Conroe will soon sweep the Netburst generation away.

It was disappointing that many of the Intel processors and boards seemed to disallow downward adjustments of the CPU core voltage. Small reductions in Vcore cannot improve power demand dramatically, but even small power reductions in power and heat would be welcome.

The Core Duo is a delightful exception in Intel's camp, with probably the highest performance-per-watt ratio of all the processors in our survey. Our experience with the AOpen / Core Duo combination leaves us eager to see more of these products in the market, both components as well as complete systems. The Core-Duo powered Apple 17" iMac — a sample of which we've been assessing for almost two weeks — has been an eye-opener about the kind of power efficiency, acoustics and performance that can be achieved today at a moderate price with intelligent system design by a mainstream computer maker.

The one set of data that surprised us was the estimated watt-hour rating of the various test systems. There was a greater than 1:2 ratio between the lowest and highest power system in idle. The ratio jumped to 1:4 when the systems were in full load. But in estimated average power consumption, the ratio dropped back down to 1:2. It tells us that idle power consumption is the single most critical aspect of energy conservation in computers. Sleep mode may be even more important than improved power supply efficiency.

As stated earlier, this article is a snapshot of the current desktop processor scene taken from a particular angle. In just a few months, new processor lines from AMD and Intel will have transformed the scene. It will be time, then, for another processor survey.

Many thanks for the generous assistance of:

Intel for processor and motherboard samples
AMD for processor samples and the Extech 380803 AC power meter
AOpen for the i915Ga-HFS, 975Xa-YDG and i945Ga-PHS motherboard and AeolusPCX6600-DV128LP graphics card samples
Asus for the A8N-VM CSM sample
FrontierPC for the Intel 630 sample.
NCIX for the MSI RS482M-IL motherboard sample
Corsair and OCZ for the RAM in the test systems
Seagate, Samsung and Hitachi for the notebook hard drives used in the test systems

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SPCR Articles of Related Interest

The State of the Industry, March 2006: Through Silent Eyes
AMD Turion 64 on the Desktop

Quiet OC'ed Pentium D 830 System
Cool'n'Quiet PC for Torrid Thailand
CrystalCPUID: User Configurable Cool 'n' Quiet
CPU Undervolting & Underclocking Primer

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