Time is Money
It’s Not Speedy Being Green: Why Seagate is Ditching the “Low-Power” HDD Market
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The formula we need is:
wattage x hours used ÷ 1000 x price per kWh = cost of electricity
Forty percent of 2500 hours is 1000 hours in 8.0W active mode. In August 2011, the average residential cost of electricity was 12.17 cents per kilowatt-hour (kWh). We divide by 1000 to convert from watt-hours to kilowatt-hours. Thus our first equation is:
8.0W x 1000 active hours ÷ 1000 x $.1217/kWh = 97 cents
Barracuda idle cost:
5.4W x 1500 idle hours ÷ 1000 x $.1217/kWh = 99 cents
So our total cost to operate a 7200 RPM Barracuda drive in an average consumer PC is $1.96.
Quickly, the costs for the green LP drive are:
5.8W x 1000 active hours ÷ 1000 x $.1217/kWh = 71 cents
4.5W x 1500 idle hours ÷ 1000 x $.1217/kWh = 82 cents
The cost to operate Seagate’s 5900 RPM green drive in the same consumer environment for one year is $1.53, marking a 43 cent savings per year.
What if you’re a remarkably compute-intensive consumer? Or perhaps the system is in a commercial PC environment, where constant productivity is emphasized. In such cases, perhaps only about 10% of the time might be spent in sleep mode. Let’s rerun the numbers.
Barracuda: $2.35/year
8.0W x 2250 active hours ÷ 1000 x $.1217/kWh = $2.19
5.4W x 250 idle hours ÷ 1000 x $.1217/kWh = 16 cents
Barracuda LP: $1.73/year
5.8W x 2250 active hours ÷ 1000 x $.1217/kWh = $1.59
4.5W x 250 idle hours ÷ 1000 x $.1217/kWh = 14 cents
Even in this remarkably heavy desktop use scenario, the savings from running the green drive is 62 cents.

Meanwhile, according to Seagate, one can expect a green drive to perform “up to 30% to 40% slower” than a standard 7200 RPM drive. If you’ve ever sat around waiting for Windows, game levels, or any large application to load from a 5400 RPM drive, you’ll understand instantly how slower drives translate to lost minutes. It seems unfair to think that 30% slower drive performance translates linearly to 30% lost productivity, so let’s say there’s an entire order of magnitude of difference. If an ordinary user is active for 1000 computing hours per year, and only 3% of that time is sacrificed due to slower green drive performance, that’s 30 hours lost per year. Still sound unrealistic? Fine, let’s slice it by another order of magnitude. Even if running a green drive meant three hours of use lost per year, with an average American wage of $20/hour, that’s $60 of wage-based productivity lost in the name of 43 cents of saved electricity. Of course, the value of user frustration plus all of the extra time wasted because the user flipped over to doing something unnecessary while waiting for that green hard drive should be figured separately.