Comments on: CNET's power testing goes live in desktop reviews

Our first batch of desktop power efficiency tests are live

[NewsReader_]

The iMac is $400 more than the Lenovo.

Congratulations Rich, it a PC. Go Green and save some green :-)

[kevinm6]

Yeah congrats on getting a computer with the old 2.0 Dual Pentium processor and intel graphics. iMac has 2.66 Core 2 Duo and NVIDIA 9400m. So expect rich to pay another $799 in a year.

[pithenumber]

@kevin
the processor is a Pentium DC [Core based] not a Pentium D [P4 based]
so its not old

but still, the iMac is faster

[rhbrown]

Lenovo has a great showing here, no doubt, and you also a good point about price. The 20-inch iMac is Apple's least expensive all-in-one, but at $1,200 it leaves ample room for more affordable competition.

I'd only point out that while the 20-inch iMac has a smaller screen than the 22-inch Lenovo, the iMac is significantly faster. Windows/Mac stuff aside (a large request, I suppose) there's a clear big picture trade-off between the two. Larger screen/lower price for the Lenovo vs. faster performance/slight efficiency edge for the iMac. I'm not sure there's an outright winner between the two. Depends on your needs.

For a more decisive match-up, check out the Dell Studio One 19 vs. the 20-inch iMac. The iMac is faster, has a larger screen, costs only $175 more than the $1,024 Dell config we reviewed, and uses a lot less power. The Dell's only advantages are its touch screen (a thin lifesaver at best), the fact that you can configure a less expensive model, and its Blu-ray option if you want to pay an extra $150 (although if you want an all-in-one with Blu-ray at that price I'd point you to the Vaio JS250J). At these prices, and with these configs, it seems to me like a pretty clear win for Apple.

[heulenwolf]

Good job Rich and CNET. Comprehensive, reasonable power efficiency ratings have been missing from many review sites for a long time. The only thing I don't understand is why you aren't publishing the equation you use, as in, "We use our own variation of the EnergyStar equation to get the raw annual kilowatt hours (kWh)." Doing so could take your rating from being just a number to being a standard. It also helps make your results verifiable and comparable with 3rd party results. When I see a different power efficiency rating from a competing review site and all I know is that the test equations are different but not what they are, I'm left with more confusion and less information than if both sites hadn't bothered to report power efficiency ratings. Data without context is indistinguishable from noise. Data with "trust us" context requires independent verification. Data in the context of published acquisition methods and standards helps make it trustworthy and quickly becomes information.

[rhbrown]

I'd actually planned to add the equation to our Desktop Power Efficiency Guide today (http://reviews.cnet.com/green-tech/desktop-power-efficiency/). I don't mind putting it up here now, though.

Here's EnergyStar's equation for annual kWh for desktops, in handy Excel format:

(8760/1000)*((Off watts*.55)+(Sleep watts*.05)+(Idle watts*.4))

You can find that formula on page 26 of EnergyStar's 5.0 Computer Specification PDF: http://www.energystar.gov/ia/partners/prod_development/revisions/downloads/computer/Version5.0_Computer_Spec.pdf

8760 represents the number of hours in a year. We divide that by 1000 to get to the annual kilowatt hours once we multiply the result by the wattage.

We use the above formula to figure out whether a system is indeed EnergyStar 5.0 compliant, according to what EnergyStar calls its TEC (typical energy consumption) rating. Each kind of system has a different TEC rating, which further varies depending on the amount of memory, whether it has a discrete graphics card, etc.

Here's our formula, factoring in our custom made load test:
(8760/1000)*((Off watts*.55)+(Sleep watts*.05)+(Idle watts*.35)+(Load watts*.05))

As you can see, we took a bite out of EnergyStar's annual Idle time estimate and added in our load test. We then multiply that figure by the national average cost for kWh ($0.1135), to get our annual cost figure for each system.

For our load test, a variation of our Multimedia Multitasking test, described here (http://reviews.cnet.com/4520-6603_7-5020816-1.html), we don't really think the average consumer will spend 1.2 hours per day (or 438 hours a year) simultaneously converting an HD movie for an iPod while also converting a bunch of MP3s to ACC files. But given the relatively low dollar amounts involved, we felt that modeling the actual energy costs was less important than showing the differences between systems with a reasonably taxing workload that will run on most computers, regardless of whether they use Windows or OS X. The dollar figure is mostly there to provide a rough guide, and you'll likely never see us factor that amount into the price comparison between systems.

Both our load test and the weight we've given it are of course debatable. And the difficulty in coming up with a universal load test in part explains why EnergyStar doesn't have one of its own yet, although we know that's one of EnergyStar's goals. We also plan to come up with a 3D load test for gaming systems, and we can adjust both the test and our formula as necessary if we decide we need to.

Who cares ? I need a computer, I buy one and plug it in, it takes electricity to run it, they send me a bill, I pay it. What's the problem ? So I can save a dollar a month if I buy the energy efficient. My truck gets 7.5 mpg. I will not live long enough to buy a twenty five grand truck and see the savings in gas pay for the new truck.

Climate warming - a joke. Windmills and solar are not going to power my computer anytime soon.

[gadgetplanet]

Its people like you who are just ignorant and can't except anything that makes your life a little less convenient.Global warming is a joke - you are one intelligent ape aren't you.Solar panels and windmills won't power your computer because its not a priority for trailer parks."i want computer,i by computer,pay with money,i pay bill,whats the problem".If you can't see past that than your the problem,seriously where do you guys come from.

[bensagenius]

Whenever I see "green," "go green," "carbon footprint," or "going green," I completely ignore the article or advertisement which features those words. It's all generally just pandering nonsense.

[Dango517]

$12.00 or $30.00 a year is roughly a $15.00 difference. So, big deal!

This might be how many might respond to your analysis. To them I'd say .................. it all adds up! An extra $10.00 here, $50.00 there and before you know it your spending hundreds and thousands more dollars then others on energy. You owe it to yourself to save that hard earned money by going "green".

What I'd really like for you to check is refrigerates. These 24/7/365 ice boxes can consume loads of power and are always on. Big saving can be had by replacing a 15 year old fridge.

Hmmm, what about pilot lights on water heaters and furnaces? Are there any possible saving there or more importantly any alternatives to pilot light?

Good first effort by Cnet.