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[sevenlayermuddle]

I have an HP Proliant server, pedigree circa 2009, that runs 24/7.   It is loaded with  3 USB TV tuners, and 4 HDDs, running Linux.   

Once I managed to get disk spin down working properly, consumption came down to 60-ish Watts when idle.   Spin up the disks, and kick of a big build job, and it will easily rise to twice that figure and more.

I fully recommend one of the cheap power meters, mine came from Maplin a while ago but I'm sure they can be got at Amazon etc too.   I use mine a lot and it blows a lot of myths about how much devices consume.   Just make sure you get one that measures Watts as well as VA.

[Dray]

I just bought a 100w equivalent Ledare LED 1000lm 13w LED from IKEA

[NewtronStar]

We have a smart electric meter which lets you see your current wattage and whole lot of other stuff like carbon foot print and so on, so I know the power draw of each and every device and my PC comes in at 100 watts the fridge uses 115 watts when the motor kicks in, you wouldn't want to leave your immersion heater on 24/7 coming in at 3 kilowatts an hour.

[sheddyian]

I have something like this http://www.amazon.co.uk/Plug-In-Power-and-Energy-Monitor/dp/B000Q7PJGW that I got from Lidl a while back, which I used to get my wattage stats from running the Raspberry Pi.

It's interesting to watch the numbers jump about if you plug a PC into it, to see what changes you can make to the O/S to make it consume less power when idle.

I set the Raspberry Pi to spin it's hard disk down when idle, as that was the major consumer of power in the setup.  I recently changed the 2 old 250Gig disks with one "green" 1 terabyte, and it draws noticeable less current, plus it's very quiet - you can't hear it spinning up and it's hard to tell if it is spinning or not.  The old ones made quite a noise!

Ian

[NewtronStar]

I set the Raspberry Pi to spin it's hard disk down when idle, as that was the major consumer of power in the setup.  I recently changed the 2 old 250Gig disks with one "green" 1 terabyte, and it draws noticeable less current, plus it's very quiet - you can't hear it spinning up and it's hard to tell if it is spinning or not.  The old ones made quite a noise!

Ian

I am getting quite excited to receive & start setting up the RPi B+ starter kit,
do you still need a Hard Disk to use it ?

[loonylion]

I am getting quite excited to receive & start setting up the RPi B+ starter kit,
do you still need a Hard Disk to use it ?

You never did, you can use the sd card instead.

[NewtronStar]

I am getting quite excited to receive & start setting up the RPi B+ starter kit,
do you still need a Hard Disk to use it ?

You never did, you can use the sd card instead.

Ok that's good just use the SD card and suppose I could use the RPi as a media center recording TV channels by adding a Hard Drive very interesting.

[sheddyian]

Ok that's good just use the SD card and suppose I could use the RPi as a media center recording TV channels by adding a Hard Drive very interesting.

There is lots you can do with it, depending on what you want to do 

The Pi is designed to work from an SD/Micro SD card.  The hard disk thing is slightly more complicated (involving a power supply, USB to SATA adaptor and a bit of tinkering), but useful for storing large amounts of data eg a server. 

I have a Pi that is running RaspBMC media centre from an 8gb SD card, it plays back video that I've recorded from my satellite receiver, or ripped from DVDs.  The interface is quite pleasing (the TV remote controls everything via the HDMI cable if your TV is relatively modern), and the picture quality is very good indeed.  Much better than the upscaling DVD player I used to have.

The media my media centre PI plays is stored on another pi, the one with the hard disk attached.  It runs various things to share the data out in a number of ways, including MiniDLNA, which means I can listen to any of the music or radio programmes on there on my mobile phone in the house, or indeed play any video on the phone or on a DLNA compliant TV / DVD / Bluray device connected to the network.

Recording TV - yes, very possible, and not very expensive - there are USB "Freeview" sticks that the Pi supports, and you can watch/record TV via them, prices around £10 I think.  I've not got one, I record TV via a much more convoluted route, but keep thinking I might add one to the Pi for completeness.

You can watch the BBC iPlayer via the Pi's RaspBMC media centre via an add-on bit of software, there's even a way to record programmes from the BBC iPlayer via a command line utility

I find setting up / using the Raspberry Pi a sometimes frustratingly steep learning curve, and I'm still a noob with Linux, but there's *loads* of stuff on the net that walks you through setting things up, and I find it very interesting.  And there are plenty of knowledgeable people here (who I've relied on on a number of occasions!)

Ian

[Ducky]

Mmm, interesting now you mention it.  I have had a laptop running 24/7 for the last 7 months....but I don't think the power draw is that high, I might turn it off for a few months just to see what difference it makes to my bills! 

I've got a R-Pi kicking around too, so be handy if I could use that for monitoring the modem instead.

[Chrysalis]

bear in mind I never tested my new rig, which is a intel haswell, my previous tests were on the i5 750.

[oldfogy]

Although not from this particular seller (unfortunately because these are now cheaper than the ones I bought)

But I bought a couple of these energy monitor devices fairly recently, but one of the best bits is you can also input your tariff and it will on a running basic display the updated calculated amount for you.
Obviously it also does a few other things, most of which we never seem to need, but I suppose it's just another selling point.

Another good feature is that it also retains it's reading when unplugged, so if it's plugged in somewhere awkward, then you can unplug it to see the readings, because unfortunately the only downside to it is it does not have a back-light display.

Another useful feature is although it can remain plugged in constantly monitoring things, it only calculates how long the item has actually been running, so for arguments sake although my kettle is left plugged for 24hrs into the device it only registers when the kettle is actually working and not the whole time it's actually plugged in, so maybe only display a 1hr usage and cost for the 24hr duration, unlike the device from Maplins in a earlier post. (which I also have but now find this one far better)

The only 2 downsides are:
1. No Back-light.
2. Having to use a pointed object such as a ball point pen to re-set the device, as there is no other re-set button.

Other than that, well worth the money, but best to buy a spare so one can be left plugged in for a long time to get more of a accurate reading such as for the 'TRUE' computer running cost averaged at maybe over a month.

http://www.ebay.co.uk/itm/Power-Meter-Energy-Consumption-Monitor-Plug-In-Socket-Electricity-LCD-13-Amp-/311095952596?pt=UK_Gadgets&var=&hash=item486ec384d4

Unfortunately as with a lot of these energy saving monitors (which I call 'The worry Meter')
because once you start seeing what some devices are actually using even in a hibernate or average usage, such as:

Virgin Media Cable box . (30 watts)
TV .......................... (13 watts)
DVD + Movie Player .... (22 watts)
Modem + Switcher ..... (27 watts)
Nas Box ................... (43 watts)
USB Backup Drive   ...... (23 watts)

It makes you want/think about turning things off, actually I DID, for a whole month and made a month's saving of about £10.
(Although there were a few other items apart from those listed above)

Unfortunately though, the Nas box does not always like being turned off even when turning off in it's own program, so sometimes turning off the mains was called for, or when turning back on and the modem wants to dish out different IP address's to other bits of the equipment (printer etc), so bit-by-bit I have stopped turning off the Modem/Router, Switcher.

But as for the monitoring device, I would highly recommend it.

[burakkucat]

Thanks, OF. It is always interesting to read the experiences of someone who is known . . . It also assists when considering recommendations.

[oldfogy]

Not sure if it's also worth looking at this old thread with regards to:

Leave modem on or off?
http://forum.kitz.co.uk/index.php?topic=12582.0

************
Way off topic, but another gadget I love are my 'Remote Controlled Socket's'
Sure makes life simple last thing at night for turning off hard to reach sockets.
http://www.ebay.co.uk/itm/380877677147

[NewtronStar]

Well have had the Raspberry PI b+ up and running collecting and transmitting modem stats for just over a week using Dslstats don't even need to turn on the desktop pc to see how my line is doing, though the Pi will not take the place of the desktop it will save me money running stats 24/7 365.

The PI B+ seems to be using 1.25 watts thats just a bluetooth usb adapter plugged in for the mouse & keyboard so the annual usage for this raspbian pc works out as 1.25 watts per hour * 24 (day) = 30 watts * 7 (week) = 210 watts * 4 (month) = 840 watts

So thats 840 watts used in a month now to get the total used in 1 year 840 watts * 12 months = 10080 watts (10.08 kilowatts) in real money that works out as 10.08 * (unit price) for me it's 0.156p or 15.6 pence = £1.57p 

[sevenlayermuddle]

I think perhaps it is time to point out the difference between power (in this case measured in watts) and energy (in this case measured in watt hours, or kWh as the case may be).

The distinction is important as it is energy that you get billed for, not power.  It is also important as  energy is subject to a law of conservation.  It cannot be created or destroyed, merely converted into different forms.

Energy 'consumed' by electrical devices is almost entirely converted into thermal energy.  As such in winter months the effect of switching of these devices will be to create a heating deficit that, averaged over time, will cause the heating thermostat to trigger earlier.  Thus the energy used by your central heating will simply increase to match, and negate, the apparent 'savings'.

Above equation is of course compromised by the fact that a PC on 24/7 may be producing heat when you have no need for it, such as summertime or winter nighttime.  Also, a tiny bit of the energy escapes in other forms, like the odd photon that drifts out through open curtains. Nevertheless, the energy savings that 'Green' politicians and etc claim can be made by low power light bulbs and the likes are IMHO vastly exaggerated.