Windows 8 and 8.1 Forums


How much power(in Watts) does my pc Consume?

  1. #1


    Delhi, India
    Posts : 58
    Windows 8 Pro, Windows 8.1

    How much power(in Watts) does my pc Consume?


    I have a 15 watt LCD Monitor, 50 Watt Speakers, 15 watt printer, 5 watt modem. All I want to know is how much power does my CPU Consume. Specs-
    Motherboard- Asus P5KPL-AM/PS
    HDD- ST3500418AS ATA(500 GB)
    GPU- NVidia GE Force 8400 GS
    Processor- Intel Core 2 Duo E7500(2.93Ghz) Overclocked to 3.54 Ghz

      My System SpecsSystem Spec

  2. #2


    There are so many variables, I doubt if anyone can do other than guess. I would suggest you buy one of those very cheap plugs which calculates your ingoing usage. You place it between your principal input power source, and you outgoing connection(s)
      My System SpecsSystem Spec

  3. #3


    Posts : 18
    Win7 x64 Ultimate, Mac OS X 10.6.8


    This is what I use.

    P3 - Kill A Watt
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  4. #4


    Posts : 1,308
    Windows 8 enterprise x64


    You can use a PSU calculator like this one eXtreme Power Supply Calculator , but they don't give exact measure, they are very generous probably because they are sponsor by Power Supply company who like to see you purchase a bigger one.


    Now the kill a watt, those cheap thing don't do a good job with switched mode PSU like the computer one , they give false results because they try to give you an estimate on the True Power ( watts ) base on the Apparent Power ( VA ) the VA of Switching power supply is not a good indication.

    In, my Electronic lab I use a real watt meter, those instrument cost over $ 1000 and can be use with switching PSU, on my PC bench, I use a good old Analog Ammeter, and I compute myself the watts (
    power in watts = voltage in volts x current in amps. ) this beast can read up to 200 A



      My System SpecsSystem Spec

  5. #5


    Posts : 18
    Win7 x64 Ultimate, Mac OS X 10.6.8


    The OP is definitely not interested in investing $1000 for a lab grade device. Granted the P3 Kill-a-watt is not a precision instrument, but it does provide the user sufficient accuracy to determine power use.
      My System SpecsSystem Spec

  6. #6


    Posts : 1,308
    Windows 8 enterprise x64


    Quote Originally Posted by Stratos View Post
    The OP is definitely not interested in investing $1000 for a lab grade device. Granted the P3 Kill-a-watt is not a precision instrument, but it does provide the user sufficient accuracy to determine power use.
    Please don't use the word accuracy with a $ 20 instruments. the voltage are not in phase with the Amp on a switching PSU, so you can't use the same power ratio to calculate the watts as a in a refrigerator case as example. From my own experiments the Kill a watt give 50% error in the reading.

    Sorry for me I see no point to make a measurement with the wrong instrument. I have not graduate from college in electronic for use the wrong thing. They are no need to purchase something at $ 1000, I pay $ 20 on ebay for the analog Ammeter on the pics. ( brand new they was costing over $ 1000 at the time)

    here what the OP need; ( it's an AC Ammeter)

    Weston Model 904 AC Ammeter | eBay
      My System SpecsSystem Spec

  7. #7


    Posts : 18
    Win7 x64 Ultimate, Mac OS X 10.6.8


    That's why I said "sufficient accuracy" meaning "it's close enough".

    The OP is not an electrical engineer which I suppose you are. Not everyone needs a precision measuring device. For example I've worked in IT for a very long time and have used tools made by Fluke to test network connections which costs upwards of a down payment of a new car. Does that mean everyone needs such a tool just to see if a cable's terminated (pinned) correctly and has good continuity? No, in fact a cheap $10 tester is more than sufficent for most people.

    Why an analog ammeter and why does it need to be something made in the 1950's which isn't even calibrated? (Look at the pic in your ebay link.) Seems to me if you're going to preach accuracy it'd be better if the recommendation was for a digital device with a simple and easy readout for the OP to clearly see how many watts his devices are using.

    Reading the OP's post, he appears to want to know how much power (watts) his equipment is using, possibly to help him determine electrical costs for keeping them on, I don't see anywhere in his posts stating he's interested in doing calculations based on ampere measurements using a $1000 analog meter. Besides your ebay link shows the device costing $55, not $20.

    I'd be interested in you proving that the P3 device has 50% error in readings. Seems to me your interest is merely to brag about being an internet expert about electronics and not to genuinely help the OP.


    P3 Kill a Watt Model P4400, 800 reviews, 4.5 of 5 stars. $20.36 on Amazon.com
    Amazon.com: P3 International P4400 Kill A Watt Electricity Usage Monitor: Home Improvement FOR 110V ONLY.

    NOTE: Just noticed the OP is from India, not sure what kind of electrical plug/voltage he uses.

    Although I have no experience with the following device, I took the time and researched a few options if the OP is in India. There will be a need for a plug adapter if his plug doesn't match.

    UK's version of the Kill a Watt, 240V. Price is 16.99 or about $26.21 57 reviews, 4.5 of 5 stars. Plug-In Power and Energy Monitor: Amazon.co.uk: Electronics

    Other options in Amazon UK's listing, but most don't have enough reviews or lack any. Amazon.co.uk: energy watt meter
    Last edited by Stratos; 07 Jul 2012 at 11:05.
      My System SpecsSystem Spec

  8. #8


    Posts : 1,308
    Windows 8 enterprise x64


    Quote Originally Posted by Stratos View Post
    NOTE: Just noticed the OP is from India, not sure what kind of electrical plug/voltage he uses.
    I know this one ( I travel a lot) , in India they use 220 volts , and like many place in Europe and Asia, it's 50hz not 60hz like in North America.


    Quote Originally Posted by Stratos View Post
    Seems to me your interest is merely to brag about being an internet expert about electronics and not to genuinely help the OP.
    I give also a free idea in my first post; the OP just have to use the link I give for the PSU calculator, it will give around 20% more, way better than spend 20$ on a kill a watt that give 50%

    I just fill the need to inform people that a Kill a watt is not design for the kind of PSU a computer is equip , you just waste your money. They do not produce accurate results for switching power supplies Unfortunately alot of people just assume it works. But for a reading of100 watts with the power factors you should read something between 50 -70 watts



    To the OP; don't forget to include the core voltage of your CPU, since you OC it's very important, you have also to include all the fans, HD, DVD and Ram.

    eXtreme Power Supply Calculator
      My System SpecsSystem Spec

  9. #9


    Posts : 18
    Win7 x64 Ultimate, Mac OS X 10.6.8


    Quote Originally Posted by area 66 View Post
    I just fill the need to inform people that a Kill a watt is not design for the kind of PSU a computer is equip , you just waste your money. They do not produce accurate results for switching power supplies Unfortunately alot of people just assume it works. But for a reading of100 watts with the power factors you should read something between 50 -70 watts
    There's no indication by P3 International (the company) which clearly states it won't work on computer PSU's and you haven't provided any data to backup your claims. A computer switching power supply is nothing more complex than taking input voltage (from your wall as AC voltage) and converting it into lesser multiple DC voltages for the computer hardware.

    You said that a lot of people assume the P3 KAW works yet you're expecting us to assume the P3 KAW doesn't work based on your word without providing any data to support your claim. I don't believe I'm being unreasonable to ask for concrete data to support your claims. You said its accuracy is off by 50%, I'm still waiting to see proof of your claim as I stated earlier.

    The ebay link you provided was for a collector's item not recommended to be used as a precision instrument. You said it was $20, on the ebay page I see that it's $50. Next it clearly shows on the product that it's not calibrated, which means its accuracy is in question. Third it was made in the 1950's, why must the OP use some antiquated test device when there are much cheaper modern options available?

    Click image for larger version

    Finally your PSU calculator link is only a tool to help the user pick out the right PSU for their configuration, not used to measure how much electricity it's actually using. The OP clearly asked "how much power does my CPU consume", not "what kind of PSU should I be using for my setup".
    Last edited by Stratos; 07 Jul 2012 at 17:35.
      My System SpecsSystem Spec

  10. #10


    To SDHamija.
    You may have been confused by the hi tek argument that followed your post. I assumed your question was general and you wanted a approximate (with reasonable accuracy.)
    SWtratos was the most realistic answer, if that was the case, but (could be mistaken) I believe that particular model is for the US, and is only for 110V. Stratos does say in a later post that you can get a 230V version from the UK - or anywhere in Europe. But there are many available which will suit you, and quite cheap. Here is one, for example, closer toyour home. It is similar to one I can purchase in my country, and does the job.

    [WTS] Personal Watt Power Energy Consumption Meter
      My System SpecsSystem Spec

How much power(in Watts) does my pc Consume?
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