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Power Usage Benchmark

Updated: AMD 785G: The Venerable 780G, Evolved
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AMD has claimed great power savings with the 785G chipset and its Powerplay feature. Let's see how the platforms compare:

Now this test isn't an ideal way to compare the 785G to the 780G, as we only have a 790GX board on hand and underclocked it to simulate the 780G specifications for this test. However, the power draw difference is so slight between the 785G and simulated 780G that we doubt there'd be much of a difference with an actual 780G board.

Comparing platforms, it looks like the E7200 CPU on the Intel LGA 775-based boards uses less power than the Phenom II X2 550, which is no surprise, as the Phenom II X2 is a much faster CPU with a lot more cache. The Athlon II X2 250, however, sips even less load power than the Core 2 Duo E7200.

Analysis

Now, I'm all for environmental friendliness, but all too often I think the bottom line cost for an end-user is overlooked. So let's examine the power savings of the E7200 over the Phenom II X2 550.

At idle, the Phenom II X2 is drawing the highest load: 92 W on the 790GX motherboard. In contrast, the E7200 is drawing 66 W on the most efficient platform, Intel's G45. It looks big on the chart, but it's a difference of 26 W.

In the most populated coastal cities of the United States, electricity costs are the highest in the country at about 15 cents per kilowatt/hour. With this information, we can calculate the cost to use the Phenom II X2 550 compared to the Core 2 Duo E7200.

Let's compare the worst-case scenario, a PC with a Phenom II X2 550 and a 790GX motherboard, to the best-case scenario, a machine with a Core 2 Duo E7200 paired with a G45 motherboard. If you left a Phenom II X2 550/790GX-equipped PC in active idle state for 24 hours a day, you would be billed $34.16 more compared to the E7200/G45 in electricity costs every calendar year, and that's assuming you leave your computer on in an active state and don't turn it off or let it enter sleep mode.

This equates to big numbers for massive corporations deploying thousands of PCs, but for the home user it shouldn't be as much of a concern. In a home environment, I'd recommend the faster processor so that the performance is there when you need it. As for environmental concerns, Mother Earth is far better served by simply turning your PC off when it isn't being used.

There are two lessons to be learned here: first, if you really care about the environment, turn your PC off (or at least configure it to enter sleep mode) when you're not using it, and second, don't be afraid of purchasing a better processor for fear that it will cost you big money in power consumption.

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