ugleung@cs.Buffalo.EDU (Leung Lee) (06/17/89)
Hello, all,
Here is a simple question, especially for the Technies. I want to get a
formula to figure out how much electricity I am spending on my
computer. Recently, I've been having my PC on for 24 hours a day with
my modem hooked up to the local phone line 24 hours a day as well. I
like to know how many kilowatts I consume and how much it would cost
me given the following configurations:
a) 220V power supply for my 386 PC,
b) 2400 modem hooked up to a local line 24 hours a day,
c) Nec Multisync II Monitor
d) Epson 9 pin printer turned on
Off hand I can't think of any thing else that the PC consumes, I
suspect the cost is relatively low since no literature hasv commented
on it indicate such costs are negligible in light of our average
monthly electric bill. Is this true?
Thanks
Leung
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===============================================================================jrr@svax.cs.cornell.edu (Jim Russell) (06/17/89)
In article <6566@cs.Buffalo.EDU> ugleung@cs.Buffalo.EDU (Leung Lee) writes: >I like to know how many kilowatts I consume and how much it would cost >me given the following configurations: > >a) 220V power supply for my 386 PC, I assume you mean 220W. I have a related question: Just because a power supply is rated at 220W, I don't think that is what it is actually using. Certainly a typical outlet could be considered a 1650W power supply, but the amount of electricity used depends on what's hooked to it. Does anyone know what a typical PC actually consumes? Or the power consumption of the motor that keeps the hard disk spinning (which I would guess to be the major power sink)? - Jim
akm@uoregon.uoregon.edu (Anant Kartik Mithal) (06/17/89)
In article <29060@cornell.UUCP> jrr@svax.cs.cornell.edu (Jim Russell) writes: >In article <6566@cs.Buffalo.EDU> ugleung@cs.Buffalo.EDU (Leung Lee) writes: >>I like to know how many kilowatts I consume and how much it would cost >>a) 220V power supply for my 386 PC, >I assume you mean 220W. >I have a related question: Just because a power supply is rated at >220W, I don't think that is what it is actually using. Certainly a >typical outlet could be considered a 1650W power supply, but the amount of >electricity used depends on what's hooked to it. Does anyone know >what a typical PC actually consumes? Or the power consumption of the motor >that keeps the hard disk spinning (which I would guess to be the major >power sink)? Jim, you are correct. A 220 W powersupply can *deliver* 220 W if so required. It would generally deliver a lot less, unless you have a computer that has lots of options added to it. The *only* way to figure out what your computer is using up is to connect it in series with an ampmeter (which I would do, but don't have one handy...), and multiply the current with the input voltage: e.g. 0.5A (shown by the ampmeter) * 110 V for the line voltage. Some other considerations. I think that it is likely that the cooling fan, and the motherboard + memory boards are the power hogs. The more memory you have in you machine, the more power it will use, and the hotter it will get. If a power supply is rated at 220 W, it might be delivering, say, 100 W because that is the amount of stuff you have in your machine. It could be consuming something like 160 W to deliver the 100 Watts. i.e. power supplies are not 100% efficient, and they eat some power too. It is also likely that your computer + printer + monitor take up less power than a room full of lights... kartik -- ----------------------------------------------------------------------------- Anant Kartik Mithal akm@cs.uoregon.edu Department of Computer Science akm@oregon.BITNET University of Oregon akm@drizzle.UUCP
bill@ncsuvx.ncsu.edu (William S. Smith) (06/17/89)
In article <29060@cornell.UUCP> jrr@svax.cs.cornell.edu (Jim Russell) writes: >Does anyone know what a typical PC actually consumes? I just received a catalog from Crutchfield Personal Office with which I have no connection, neither am I able to vouch for the reliability of their data. On page 4 of their Summer/Fall 1989 catalog there is a nice color chart giving approximate power requirements for various components of a PC. Their data is: Motherboard 35 W Keyboard 2 Floppy drive spinning 10 Floppy disk idle 5 Hard Disk - 40 Meg 15 IO Card 4 Modem 4 Floppy/Hard Disk Controller 8 EGA video card 5 Memory extension (2 Megabyte) 20 Tape backup w/controller 15 Catalogs may be requested on 800-521-4050.
Ralf.Brown@B.GP.CS.CMU.EDU (06/18/89)
In article <7988@saturn.ucsc.edu>, lance@helios (Lance Bresee) writes: }So you probably use 200 watts for the computer and 180 watts for the monitor. ^^^^^^^^^^^^^^^^^^^^^^^^^ Maybe if you're using a Zenith Flat Tension Mask monitor (which uses lots of power because the screen filters 70% of the phospor's output to greatly improve contrast), but my monochrome monitor is rated at 40 watts, which means it probably consumes quite a bit less. Figure about 60 watts to be on the generous side in your calculations (my 13" color TV is rated at 65 watts, and a TV has more circuitry than a monitor), though I have seen monitors rated at only 30 watts. -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/31 Disclaimer? I claimed something? Intelligence is when you spot a flaw in your boss's reasoning. Wisdom is when you refrain from pointing it out. --James Dent
mlawless@ncrwic.Wichita.NCR.COM (Mike Lawless) (06/19/89)
Some things to keep in mind when discussing power consumption:
1) as previous posters have mentioned, actual power delivered by the supply
is likely to be less than its rated capacity.
2) power consumed by the supply will be greater than the power it delivers,
due to the less than 100% efficiency of the supply.
3) AC power consumed by the supply will NOT by AC RMS volts x RMS amps,
because the power supply is an inductive AC load; also, current is generally
not sinusoidal in a switching power supply, which is what most PC supplies
are (the current waveform is more like a series of spikes than a sine wave).
Therefore, the power factor is somewhat less than 1. I read a recent article
about power factor correction techniques in switching power supplies, which
is required in order to get higher capacities without causing excessive
current draw on a 15 or 20 amp circuit.
4) One piece of PC peripheral equipment which is a real power hog is a laser
printer, because of the fuser heater. I just moved into a house with older,
non-grounder, 14 gauge wiring, and whenever I turn on the printer, it dims
the lights in the entire house (I believe it draws about 8-10 amps). Moral:
don't leave a laser printer on for long idle periods.
--
Mike Lawless, NCR E&M Wichita, Box 20 (316) 636-8666 (NCR: 654-8666)
3718 N. Rock Road, Wichita, KS 67226 Mike.Lawless@Wichita.NCR.COM
{ece-csc,hubcap,gould,rtech}!ncrcae!ncrwic!Mike.Lawless
{sdcsvax,cbatt,dcdwest,nosc.ARPA}!ncr-sd!ncrwic!Mike.Lawlessjwi@lzfme.att.com (J.WINER) (06/20/89)
Anant Kartik Mithal writes: > Jim, you are correct. A 220 W powersupply can *deliver* 220 W if so > required. It would generally deliver a lot less, unless you have a > computer that has lots of options added to it. > > The *only* way to figure out what your computer is using up is to > connect it in series with an ampmeter (which I would do, but don't > have one handy...), and multiply the current with the input voltage: > e.g. 0.5A (shown by the ampmeter) * 110 V for the line voltage. No, no, no use an AC amp meter which works by induction. It has (more or less) circular jaws which close around the power cord to take the measurement. Attempting to hook a multimeter ac amp range in series with the power line is likely to get you hurt. Jim Winer ..!lzfme!jwi I believe in absolute freedom of the press. Pax Probiscus! Sturgeon's Law (Revised): 98.89% of everything is drek (1.11% is peanut butter). Rarely able to send an email reply sucessfully. The opinions expressed here are not necessarily Those persons who advocate censorship offend my religion.
rzh@lll-lcc.UUCP (Roger Hanscom) (06/21/89)
In <5381@ncrwic.Wichita.NCR.COM> mlawless@ncrwic.Wichita.NCR.COM (Mike Lawless) writes: >Some things to keep in mind when discussing power consumption: points 1, 2, and 3 deleted for the sake of brevity >4) One piece of PC peripheral equipment which is a real power hog is a laser >printer, because of the fuser heater. I just moved into a house with older, >non-grounder, 14 gauge wiring, and whenever I turn on the printer, it dims >the lights in the entire house (I believe it draws about 8-10 amps). Moral: >don't leave a laser printer on for long idle periods. Good point! Also (goes without saying??), *NEVER* put 2 or 3 (or more!) of these babies on the same 110v circuit. The fuser heaters are not on continuously, they switch on and off to maintain the heating element at temperature. Everything will go along just fine until one day the random event (all fuser heaters come on at once) will happen, and you'll wonder what happened to the lights! @:^) roger rzh%freedom.llnl.gov@lll-lcc.llnl.gov {uunet,ames,ucbvax,..}!lll-lcc!freedom!rzh Upstairs, Over a Vacant Lot, Inc.
lance@helios (Lance Bresee) (07/23/89)
You need to know either the power supply current or wattage... If you know the wattage of the power supply, Then add a rough estimate of your monitor power...volts x 1.5 if you have 120 volts or volts times .75 if you realy have 220 volts...which I seriously doubt since most house current outlets use 120 v. So you probably use 200 watts for the computer and 180 watts for the monitor. The printer is too small a drain to worry about. Total is at MOST 380 watts... you are billed by the electric company based on your use measured in kilowatt-hours..which is the number of watts you use times the number of hours divided by 1000....so in 24 house you probably use 9.12 kilowatt hours. Here in California where power is expensive that would cost you at worst..if all is counted over base rate.. one dollar and nine and one half cents per day.... peanuts! Lance
lance@helios (Lance Bresee) (07/23/89)
in reply to the previous reply.... worst case hard drive useage is probably around a half amp.. floppy's draw more typically, but arent on all the time.. motherboards draw very little...dram is also variable... the number of cards you have also effects power drain.. most designers use a power supply which will handle more than the power required by a system which is loaded to the max.. I have yet to hear of a 200w power supply being insufficient for any AT configuration.. You are probably safe to assume that an AT with two floppies,two HD's, and eight slots full of cards will use aroung 80 percent of 200w, or 160w...if you have one hd and five or so cards with two meg dram you are probably drawing 100 w... get a clip-on ammeter and isolate one of the wires in your power cord, then turn on the machine.. that is the only way to be accurate.. Monitors are also variable and probably draw more current than the rest of the setup...you can conserve a LOT of power if you leave the computer running but turn off the monitor when it is not in use... lance
Ralf.Brown@B.GP.CS.CMU.EDU (08/13/89)
In article <7993@saturn.ucsc.edu>, lance@helios (Lance Bresee) wrote: }Monitors are also variable and probably draw more current than the }rest of the setup...you can conserve a LOT of power if you leave Your monitor must be quite a power hog. My mono monitor is rated at 40W, and I've seen 30W ratings. Even my color TV is only rated at 65W.... -- UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=-=- Voice: (412) 268-3053 (school) ARPA: ralf@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/46 FAX: available on request Disclaimer? I claimed something? "Drama is life with the dull bits left out." -- Alfred Hitchcock
cth_co@tekno.chalmers.se (CHRISTER OLSSON) (08/14/89)
> You are probably safe to assume that an AT with two floppies,two HD's, > and eight slots full of cards will use aroung 80 percent of 200w, > or 160w...if you have one hd and five or so cards with two meg dram > you are probably drawing 100 w... get a clip-on ammeter and isolate > lance I run my AT (10Mhz with 640K onboard and 2Mbyte on an ext-card, 2 HD's (Nec 5126), 2 1.2M floppies, modemcard, Paradise EGA-card, 2 serial cards, 1 printer card and a DTC HD-controller ) with an old 100W PC-power supply... And i have an another machine without case but with a 50W power supply.. (It's a 8Mhz AT-mothercard with 640k memory, 2HD's (CMI 6640 and BASF 6188) , 1 360K floppy, IBM 64K EGA-card, multifunction-card and Adeptec 2010- controller). I'ld swap a fuse to get the power supply to work... :-)