# How Much Power Does A Hard Drive Use?

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How much power does a hard drive use?  Looking at the label of my WDC
120GB (WD1200JB-00CRA1) I see two indications, 5VDC-0.8A and
12VDC-0.45A.  This says to me that it draws between 4w and 5.4w DC, but
I wonder how much extra AC juice it draws given the inefficiency
inherent in the power supply.  Let's say it draws another 10w AC (120V
here in the USA).  At 10 cents per thousand watt-hours, it would cost
about 10 cents every four days in extra electricity.

This is for my TiVo, and I am trying to decide whether to add a drive
or replace the main drive.  The box runs 24/7/365, which means another
\$10 a year for two vs. one hard drive.

## Re: How Much Power Does A Hard Drive Use?

Ok, first your calculations are off a bit.  It uses about 4W of the 5V line
(5*.8) and a little more than 5W off the 12V line (12*.45)  Add those two
together, and round it off to 10W.  Poor power supplies tend to be about 60%
efficient.  So about 17W A/C is going to be used, at most.

That's about 10 cents every 2 1/2 days in electricity, or about \$14.60/year.

But that's peak currents.  Idle will be about 75% of that.  Roughly \$11 a
year, so I guess your calculations weren't too far off.  It'll be a little
more than \$11 per year because the drive won't always be idle, but it'll be
a little LESS than \$11/year also, as the power supply is probably more than
60% efficient (hopefully).

If electricity use is really so much of a concern, it might be wisest to
replace the whole TIVO box with something that doesn't need to be powered
24/7/365.  We use a non-Tivo DVR which maxes out at 46W total A/C power use
when recording and playing back simultaneously from hard drive.  It drops to
5W total A/C power use in standby mode, and that's the mode that it is in
most of the time.

I don't know how much power the Tivo box uses, but I've already figured it
uses about 17W A/C power for each hard drive alone.  That's just the hard
drive.  -Dave

## Re: How Much Power Does A Hard Drive Use?

Lots of good info there mate.  One thing seems odd and that is the
idle draw at 75% of peak.  I thought it was much less than that.
Maybe 25%?

## Re: How Much Power Does A Hard Drive Use?

Yeah, he mangled that considerably.
http://www.storagereview.com/comparison.html
The two power consumptions are in the pulldown sort list.

## Re: How Much Power Does A Hard Drive Use?

No, I didn't.  I said idle power consumption.  Sleep mode is significantly
lower, but I'm not sure that applies to DVR.  That is, I've not seen a DVR
that you could put to sleep.  -Dave

## Re: How Much Power Does A Hard Drive Use?

Yes you did.

You also said peak currents. Idle isnt 75% of peak currents.

You should have said active currents, not peak currents.

Separate matter entirely.

Varys with the DVR.

You can with mine, either at the hard drive level or the entire PVR too.

## Re: How Much Power Does A Hard Drive Use?

The disk drive manufacturers have information on their web sites.

Idle 8W       Seek 12W   (dunno how profiles are triggered)
http://www.seagate.com/docs/pdf/datasheet/disc/ds_db35.pdf

Or this one:

Idle 9.3W     Seek Average 12.6W      Operating Average 13.0W
http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_10.pdf

Also, measured idle and active power is listed here. No 750GB
drives in here yet. (Note that 12V max power is for spinup,
so can be safely ignored.)

http://www.storagereview.com/comparison.html

A 7200.10 250GB is  \$80
http://www.newegg.com/Product/Product.asp?Item=N82E16822148142

A 7200.10 750GB is \$400
http://www.newegg.com/Product/Product.asp?Item=N82E16822148134

Once the capacity is larger than the current pricing "sweet
spot" for drives, the price goes to hell. It would take a while
to pay back the \$160 price difference between 3x250GB versus
1x750GB drives. You could buy 5x250GB for the price of 1x750GB.

Also, check the reviews on some of the monster sized drives.
I've read the odd review which mentioned a high surface temp
for the big drives, implying that good cooling should be used to
get the full life of the drive.

Paul

## Re: How Much Power Does A Hard Drive Use?

Paul,

I'm still in the IDE world until I need to replace my motherboard. How
many SATA drives can you put on a single SATA controller? How many SATA
controllers are usually found on a motherboard that has native support
for SATA?

Thanks,

Bob

## Re: How Much Power Does A Hard Drive Use?

Bob wrote:

It's one connector per drive. Most motherboards come with at least
two SATA connectors if they have any at all. Add on SATA cards are
pretty inexpensive and come in ranges from 2 connectors up to 16.
Any more than 16 drives and you'll have to put in a second card.
Like IDE and USB, they come in different speeds.

Anthony

## Re: How Much Power Does A Hard Drive Use?

@nothing.like.comcast.net says...

Anthony,

Ah, so it's not like SCSI with 8 or more devices per connector
depending upon the version of SCSI :-(

But if I put in a card, I've got PCI bus speed limitations and
contention with other devices.

Do IDE and SATA controllers on the motherboard have a dedicated I/O bus
or do they also share the PCI bus?

Oh well, I'm glad I don't NEED more speed at the moment.

Thanks,

Bob

## Re: How Much Power Does A Hard Drive Use?

You can find motherboards with two SATA ports (low end chipsets),
four or six SATA ports (Intel and/or Nvidia chipset), and there
are motherboards that also incorporate a four port RAID
controller as well, which may operate in a non RAID mode.
I would say a good but expensive motherboard, might allow eight
SATA connections without any tricks.

There are also SATA port multipliers, but those will be
dependent on the software driving the original port, and
field reports on how those work are pretty scarce.

For example, this box takes a SATA port from the motherboard,
and allows five SATA disks to be connected. I think I read
somewhere that the max fanout might be 15 disks multiplied
in this way, from one port. But the thing is, the poor
BIOS on the motherboard would go nuts, figuratively speaking,
if it found 15 SATA drives sharing an ordinary Southbridge
port. So I would not buy one of these for my motherboard
today, at least until some review site experiments with the
concept a bit. Right now, a typical use for one of these, is
with a separate SATA chip on a motherboard, that only has
one or two ports. The RAID software for a select few of those
chips, can understand finding a port multiplier connected
to the port. Motherboard chipsets probably don't have that
kind of function (yet). (Imagine the mess on the BIOS
screen, if they had to find room to display the statistics
for 15 drives!)

http://www.cooldrives.com/cosapomubrso.html

As for the SATA port itself, the expectation is that a port
has a one-to-one connection to a device at the other
end of the cable. Unlike the ribbon cable used for your
current IDE drives, you won't find SATA cables with two
drives connected to the same cable. So the SATA drive is
always "master" in a way, as there is never a "slave".

In terms of SATA cables, one difference between the "old"
cables and the "new" cables, is some of the new ones have
a latching mechanism. If the motherboard SATA connector is
designed to work with the latch, you end up with a more
secure connection for the cable. Some of the early adopters
of SATA, had trouble with cables falling off. No matter
what SATA cable you buy, it should be suitable for operation
at 1.5Gb/sec or 3.0Gb/sec.

And if you like to look at expensive things you can never
afford, here is an Areca RAID controller with 16 SATA ports
on it. It is a bit less than \$1000. You can plug one of these
into the second video card slot on an SLI motherboard.

http://www.newegg.com/Product/Product.asp?Item=N82E16816151005

There is even a version of that product line, that has 24 SATA
ports on it. But it needs a PCI-X slot, which you typically
find on a server motherboard.

http://www.newegg.com/Product/Product.asp?Item=N82E16816151004

HTH,
Paul

## Re: How Much Power Does A Hard Drive Use?

says...

OK, so when I do replace my motherboard some time in the future, I can
find one that supports 4 SATA drives. As was mentioned earlier in this
thread, the price for large capacity drives, say > 500GB, gets
exponential rather quickly, so I was thinking along the lines of 4 x
250GB rather than one 750GB or 1TB. I'm a bit of a pack rat when it
comes to saving stuff :-)

I had a motherboard with a RAID chip on it a few years ago. I loved the
speed, but hated the data loss when one of the hard drives in the
stripe set died :-(

At that point, maybe I should just go straight to a fiber-based SAN :-(

Thanks,

Bob

## Re: How Much Power Does A Hard Drive Use?

It would be if the hard drive went to sleep mode.  But idle is a good
percentage (about 75%) of full current draw.  -Dave

## Re: How Much Power Does A Hard Drive Use?

Full current draw isnt the same thing as peak current.

And peak current is essentially irrelevant to the cost of the power used.

## Re: How Much Power Does A Hard Drive Use?

Mike T. wrote:

We use a non-Tivo DVR which maxes out at 46W total A/C power use

Curious what DVR you are using that goes to standby.  I already have
two TiVo's and a PC-based DVR I built myself, so not sure if I'll get
another, but still curious.  I don't think the TiVo's use more than 50
or 60 watts on average, but they always are recording so they never go
to standby.

Also, thanks to all for the great info on my original question.  These
questions are more for fun than money saving, but who knows, if
electricity goes up to 30 cents per kWH a few years down the road,
maybe things will change.

## Re: How Much Power Does A Hard Drive Use?

sorry_no_email@yahoo.com wrote:

Web Scheduler can be run like that.

Cant see it myself, since its mostly coal fired.

I doubt it.

## Re: How Much Power Does A Hard Drive Use?

On 24 Jul 2006 19:57:08 -0700, sorry_no_email@yahoo.com
wrote:

I doubt TIVOs use that much, I have a TIVO PSU here that is
rated for 60W, as 4A @ 3.3V, 2A @ 5V, 3A @ 12V, 5mA @ 32V.
I don't know for sure but expect those ratings are with a
certain CFM (airflow) and would need derated as implemented
in a TIVO.

## Re: How Much Power Does A Hard Drive Use?

We've got a pioneer DVR633HS.  It is the closest thing to a digital (VCR
replacement) that you will find.  They call it a 'DVD recorder', but it's
useless for that purpose.  (too much copy protection)  We bought it for
Tivo-like time shifting and it works fantastic for that.  Just like a VCR,
you can turn it off (standby) when not in use.  It will turn itself on to
record scheduled programs.  -Dave

## Re: How Much Power Does A Hard Drive Use?

8-10 watts total is nominal.  It will draw less when idle than when writing.
If you have a power saver option in the machine, it will shut down
completely when not in use.

## Re: How Much Power Does A Hard Drive Use?

John Weiss wrote:

To elaborate on that, your BIOS settings may have a "power" menu where
you can tell it to spin down the drives when not in use.  The main
system drive may never spin down due to writing to the system log etc,
but drives used for backing up data or recording TV shows etc. will
normally be off.  You know it's working if there is a delay when you
first access the drive after a period of inactivity.