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The Power Supply Matters!

Efficiency: Core 2 Nukes Atom On The Desktop

System efficiency does not only depend on the core components you use, but it is highly dependent on the power supply, since all power supplies have a certain efficiency when they convert 110 or 220/230 V AC power into 3.3 V, 5 V, and 12 V DC power. Depending on how complex the power supply is, and on how it is laid out (one rail, multiple rails), it will demonstrate certain efficiency characteristics.

As all PSUs have a power loss, efficiency is typically rated in percentage terms. The industry standard for measuring and rating efficiency is called 80 Plus, and it splits power supply units into three categories : bronze, silver, and gold. An 80 Plus rating approaches 90% power efficiency at varying loads, taking low, medium, and high loads into account and specifying this as a percentage of the total output.

Here’s the issue : if a 1,000 W power supply unit is rated excellent at low load, this means that “low load” is still a rather high power in the case of our two systems, which idle at less than 30 W. At such a low load, the excellent 80 Plus, 1,000 W power supply unit will show rather pathetic power efficiency just because it wasn’t designed for such a load.

We decided to run the Foxconn G31 system and the Core 2 Duo E7200 with four different power supplies that are rated at 1,000 W, 850 W, 300 W, and 220 W. You will find the results on the following page, and they should convince you to get a power supply that matches your system’s requirements, as the power requirement differences are larger than the difference in power consumption that you would get by exchanging the E7200 for a Core 2 Duo E8600.

1000 W : OCZ EliteXstream 1000

We used a high-end OCZ power supply to test power consumption for such a hardcore power supply unit. The EliteXstream 1000 is an excellent device. Designed by PC Power and Cooling, it is rated 80 Plus and offers an 82% level of efficiency. An active power factor corrector (PFC) and lots of connectors are mandatory for such a high-end product, which is targeted at workstations and high-end gaming. The device comes with an impressive five-year warranty. However, the device is overkill for our low-power systems, as you will see on the next page.

850 W : Coolermaster Real Power Pro RS850 EMBA

Cooler Master’s 850-W RS850-EMBA has been our reference power supply for almost a year. We use it for many of our reviews, as we appreciate its powerful and reliable qualities. It is also backed by a five-year warranty, is 80 Plus compliant, and definitely well-equipped for an enthusiast user’s requirements.

300 W : Etasis EFN-300

We didn’t have a power supply at 400-500 W available at the time we finished this article, but we found a 300 W model by Etasis, the EFN-300. Etasis Electronics is not one of the big, popular brands, and the EFN-300 isn’t special in any way except that it is a no-noise device rated at 300 W output. While it likely will not impress enthusiasts, the power supply unit helped to decrease the system’s power consumption compared to the Cooler Master and OCZ power units.

220 W : Fortron FSP220

If you remember our recent articles on VIA’s Nano vs. the Intel Atom and the comparison of Foxconn and Gigabyte G31 motherboards, then you might also remember the FSP220 from Fortron, which is a compact 220 W power supply.

This one is rated for an even lower maximum output and some of you might wonder why we even bothered to use it. Clearly, this is the power supply that allowed us to reach the lowest overall power consumption numbers, as it is capable of answering the power demands of the Atom and Core 2 systems at a much higher efficiency level than the other power supply units we tried.

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  • 0 Hide
    Anonymous , 21 November 2008 17:51
    What you have to understand is that the Atom is a low-end processor targetting notebooks or netbooks. You can consider it as a low-spec celeron processor and should not be compared to a C2D processor in a performance/efficiency shootout.
  • 0 Hide
    papalarge123 , 21 November 2008 18:15
    i disagree.

    i believe that it is good to show off the power efficiency of both CPU,
    although the Atom is very out classed by the C2D, it does reflect on the very efficient C2D ability.

    consider the C2D as being almost 2x faster per core with two cores to handle, the fact that the C2D can have a 30% increase of power usage with almost 400% Power ability over the atom, u start to wonder why bother with the atom at all.
  • 0 Hide
    sneakyfcknrusky , 24 November 2008 09:12
    This article seems like one they posted earlier. Have they run out of things to tell us.
  • 0 Hide
    Anonymous , 24 November 2008 20:16
    Atom is let down here by the 945 chipset, which is using most of the power... paired with the 'Poulsbo' chipset it would use a LOT less power, however may well be more expensive. AFAIK there will be Mini-ITX boards using Poulsbo so this should be revisited then...

    Atom based systems like the EEE unit (even crippled by the 945) are a lot smaller than even mATX based PCs, which is often hand-in-hand with low power system design, and the cost of a Mini-ITX Core 2 motherboard is much higher, skewing the performance per $ metric.

    The systems compared here aren't really like for like, and are in different segments.
  • 0 Hide
    BushLin , 24 November 2008 23:22
    Agree with the above, didn't make it past page two when I saw they were testing with a 945... what's that made on? 90nm? not really a fair test.
  • 0 Hide
    Anonymous , 26 November 2008 05:46
    What happened to the much less power hungry SiS chipset that Intel mentioned when they released Atom?
    No implementations of it?