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# How to: Find out the actual power usage of my computer?

I have heard this question asked quite a few times in threads....."Is there a way to calculate how much power my PC is consuming?" or "Has this power supply got enough wattage for my setup?". Until recently I thought the only way to answer the above question was to guess the power usage of your system using the separate power requirments of the components. However, this method is unreliable as it depends on:
a) the usage of the component (i.e. load or idle)
b) the state the component is in (power requirements alter as the component ages)

There is a way to continuosly measure the power usage of your system...and that is with a plug-in mains power meter. They fit into the wall socket and allow you to measure the power/voltage/current being drawn from your PC. They also work out the cost of running your PC in KWH. You enter the cost per KWH and it will calculate how much your computer is costing to run. This could be useful for people with folding farms....who want to calculate how much extra it would cost to for example add another computer.

Here is a link to show how they operate:

Another thing which must be taken into account with PSU's is the efficiency rating of the PSU. Take my Tagan U22 480W PSU for example...it has a 77% efficiency rating at full load. This means that at full load for every 100W supplied to the PSU only 77W are converted into useful power output. This must be taken into account with the power meter reading. Here is an example for my 77% efficient PSU; if the power meter reading is 300W, the PSU will actually require 300/0.77 = 390W of input power to produce the 300W of output power. Consequently, the efficiency factor is absolutely vital when calculating if your PSU is able to produce enough output power to supply your system.

Your PSU's efficiency rating should be written on the side of your PSU, but if it is not, then just google the name of your PSU and you will almost certainly find it there.

They cost around \$30, and could be really important for those with an SLI/crossfire setup who want to know if there 400W will cut it.

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AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
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Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
Well, you need to take into account efficiency...No PSU is 100% efficient, meaning 1000W may go in, but only 800 might come out on the rails...This is a big guesstimate, varying with the respective efficiencies of PSUs out on the market today.
 Burning Phoenix (13 items)
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 Burning Phoenix (13 items)
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3 WD 80GB RAID0, Seagate 500GB, WD 1TB Caviar BLCK Lite-On LH-20A1S Windoze 7 Professional Dual Dell E207WFP 20.1" Widescreen LCD's
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Logitech G15 Silverstone OP750 Lian-Li PC-A10B Logitech G5
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Thanks Burn...you are right I forgot about the efficiency of the CPU. This isnt anything major though as almost all PSU's have their efficiency ratings written on them. I will add this to the FAQ, thanks
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AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
Quote:
 Originally Posted by rustynator Thanks Burn...you are right I forgot about the efficiency of the CPU. This isnt anything major though as almost all PSU's have their efficiency ratings written on them. I will add this to the FAQ, thanks
i have a 250 watt max psu that powers a a7n8x-la mobo cdorom dvd drive xp 2800 barton two 256mg kingston dual channel 3200 mem xfx 6200 256mg vid card 3 fans dial modem card a card for faxs psu is a bestec came in a hp pavilion a259e bought sensorsview pro 2.1 off of softpedia.com a & b core volts were fine 3.3 was like 2.43 &5 was like the same adjusted them using the software whorks fine but isnt my psu kind of being overloaded.use clockgen to oc cause all i have to work with at this moment could a hec orion 485 or 585 watt 12volt dual rail help me now and next pc i build
This isn't the place for that type of question. You should start a new thread using proper English....alternatively you could do what the FAQ says and buy a power meter to find out if you PSU is undersupplying.
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
Quote:
 Originally Posted by rustynator This isn't the place for that type of question. You should start a new thread using proper English....alternatively you could do what the FAQ says and buy a power meter to find out if you PSU is undersupplying.
ok
Has anyone else bought a power usage meter and tried it out??
I bought the one they sell in MAPLINS(UK) for Â£14.99
I have a Tagan 480U22 PSU in my rig (BUGBASH)
Running just my PC and a Unitek 1650 UPS through the meter at IDLE it consumes 165WATTS (240V UK Power)
Running 3DMark06 the meter reads NO Higher than 235WATTS!!!
anyone else done any mileage? is my meter telling me Porkies?
 Raven (17 items)
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 Raven (17 items)
CPUMotherboardGraphicsRAM
XEON X5470 @ 4.0Ghz ASUS P5Q PRO TURBO XFX 5850 BLACK 6GB OCZ Reaper PC2-9200
Hard DriveHard DriveHard DriveOptical Drive
OCZ Vertex 4 128GB Seagate 500GB RAID1 Western Digital 2TB RAID1 Sony Blu Ray
CoolingOSMonitorKeyboard
Venomous X Windows 7 Home Prem 64BIT HP ZR24w, Optoma DX606, 84" Panoview HP Cheapo
PowerCaseMouseAudio
Corsair TX750v2 Silverstone RV-02 Black Logitech Trackball Essence STX
No I dont think it is telling porkies....computers just generally dont require as much power as people think they do! I am glad you tried it out....hopefully this has helped prove that in most cases a 600W PSU is overkill.
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
 My System (13 items)
CPUMotherboardOSMonitor
AMD 3700 KACAE 0602GPMW DFI LanParty nF4 SLI-DR XP Pro SP2/Vista Beta 2 Samsung SM930BF 19&quot; TFT
KeyboardPowerCaseMouse
Microsoft Tagan U22 480W Thermaltake Tsunami Microsoft
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