We’ve boosted our testing to now include 27 monitors so we’re now pretty certain we know what to expect after our final series of tests.

Our tests on Blackle versus Google has been reported on by major newspapers and sites around the world. Well, while a few people have managed to pull out a monitor or two to test how much power they consume running the two search sites, we think we’ll have to last word.

27 monitors.

Yep, we’ve tested 27 monitors, including some 23 LCD monitors, to find out once and for all how both of these search engines stack up on monitor power consumption.

We’ve taken a range of sizes and brands to try and get the most reliable test results possible.

There’s no argument that on CRT monitors, Blackle does reduce the power consumption but it’s not by the 15-watts claimed. We tested the four CRT monitors we could get our hands on and found that only one unit, an older 22-inch Compaq, showed the 15-watts or more power differential.

But with the LCD monitor market penetration worldwide now beyond 75%, it’s the LCD monitor power consumption that’s just as, if not more, important.

The most interesting aspect we found was that of the LCD monitors we tested of size 22-inches or less, all showed an increase in power consumption using Blackle. Beyond the 22-inch mark however, five of the six models showed a fractional decrease in power consumption when using Blackle, except the ViewSonic VX2835wm, which showed a 2.2-watt increase.

For the five that dropped their power consumption, the average drop was 3.16-watts, again, not the 15-watts being suggested.

But for the sake of fairness, here’s what we suggest – if you’re using a CRT monitor, you can save some power by using Blackle however it won’t be as much as its supporters will have you believe. We still think it’s around half.

If you’re using a 22-inch or smaller LCD screen, stick with Google if you want to keep power consumption to a minimum. However, if you have a 24-inch or larger LCD monitor, on average, Blackle is the cheaper option but it’s not a guarantee – as we said, we found one 28-inch LCD monitor that bucked that trend.

However, the power consumption difference between Google and Blackle on all 23 LCD monitors was as small as you could get – an increase of 100mW (0.1Watts). So after all that testing, we’re in a better position to say that anyone else that Blackle makes next to no difference, on average, with LCD monitors.

If you’re really serious about saving energy, here’s just a couple of tips that will make far more difference: switch off your computer at the end of the day and don’t bother with a screensaver, because every screensaver costs power to run.

UPDATE August 10, 2007 - If you're serious about wanting to save power with your computer, read this story. We've outlined five simple ways  based on our tests that we can all use to help save amounts of energy that far exceed what you can do with a search engine.   

Darren Yates is a B.Sc. (electronics) graduate of Macquarie University, Sydney, Australia.