Power-Saving Motherboards: Fact Or Fiction?

Analysis and Conclusion

This review isn’t aimed at the performance enthusiast. If you’re looking for the best overclockers or for a feature-loaded P45 motherboard to boast about at your regulars’ table, check out our recent 11-Way P45 Motherboard Shootout. Here, we focus on finding the best-performing, upper-mainstream P45 solution with power efficiency in mind—great per-Watt performance is key.

Using DDR3 memory instead of DDR2 on a dual-memory motherboard (ASRock P45R2000-WiFi) makes a real efficiency difference—it saves 1 W. This alone wouldn’t be extremely significant, but the other test results changed our minds: we’re shocked that the highly praised power-saving mechanisms as implemented by Asus and Gigabyte didn’t reduce idle power by more than 1 W for the Asus motherboard, 2 W for the Gigabyte model. Even at peak processor loads, the power savings don’t exceed these numbers by much.

Where the Power Savers Failed

Asus fails to reduce system power consumption at peak power. Total system power consumption actually increases by 0.8 percent (P5Q Deluxe) or 1.6 percent (P5Q-E) when the EPU-6 power saver is set to Auto. The more aggressive power-saving modes save power, but they also impact performance by lowering clock speed. Gigabyte’s EP45-DS3R board introduced power savings, but they were minor.

Conclusion

We didn’t evaluate every P45 motherboard—we focused on those that integrate power-saving mechanisms—and one board without to use as a baseline. Most of the products we tested are weak when it comes to decreasing system power in idle and at peak loads when compared with conventional motherboards lacking "green" functionality. In all cases, Intel’s processor power-saving Enhanced SpeedStep and other CPU power-saving options were enabled—those are the default settings for the vast majority of motherboards. The first conclusion is simple: check that all processor power-saving options are enabled and you’ll be getting most of the power savings your platform is able to offer already.

Our second conclusion may be disappointing for the big motherboard manufacturers: most approaches to power saving don’t provide much benefit. Gigabyte manages to save power with DES in its GA-EP45-DS3R. Neither Asus nor Gigabyte provides much savings—at least with the Core 2 Duo E7200 we used in our tests. Other, more powerful processors (Core 2 Quad or Extreme, for instance) might change this result in favor of the multiphase voltage-regulator arrays provided by Asus and Gigabyte. But that’s not a good processor choice for high-efficiency PCs. The results and the testing approach should be discussed, as processor preferences vary widely—but bottom line, don’t expect too much.

ASRock’s and especially Foxconn’s largely conventional motherboards did a good job—they almost kept up with most of the self-declared power savers. Only MSI’s P45 Diamond showed decreased system power requirements in both idle and peak load conditions, making this the only P45 motherboard with dynamic voltage-regulator switching that truly benefits users. Others may follow suit as they optimize their products for low-end processors such as the Core 2 Duo E7200 we used in our tests, but the conclusion at this time is obvious: save your money and purchase a conventional motherboard or go with MSI’s P45 Diamond. Basing your purchasing decision on the promise of significantly reduced consumption probably won’t pan out.