Hard drive spec change

Bryn M. Reeves bmr at redhat.com
Thu Mar 11 10:33:38 UTC 2010


On Wed, 2010-03-10 at 19:11 -0800, John Reiser wrote:
> > MultiGHz, Multicore CPUs consume magnitudes more power than HDs.
> 
> Not always.  A typical 3.5" harddrive consumes about (max):
>      0.65A *  5V =  3.25W
>      0.50A * 12V =  6.00W
> which totals 9.25 Watts, and less when not transferring data.
> I am composing this message on a system with a 2.5GHz, two-core
> processor that consumes 45 Watts maximum, and less when "idle".
> So in this case the ratio is closer to 5:1, not 10:1.

That doesn't compare to figures that I have seen - a lot of 7200rpm hard
disks will draw up to a couple of amps on the 12v line (at least, during
startup) giving you peak power consumption in the 20-30W range. The
lastest data sheets I can find for Seagate's Baracuda 7200 drives for
e.g. quote a maximum draw of 2.8A (33.6W).

Admittedly that's a peak value and not an average but so is the 45W
processor figure; I think claiming that modern CPUs consume "magnitues
more power" than modern hard disks is not justifiable.

Regards,
Bryn.




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