Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!uoregon!akm
From: akm@uoregon.uoregon.edu (Anant Kartik Mithal)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Power Supply Calculation:
Message-ID: <4917@uoregon.uoregon.edu>
Date: 17 Jun 89 03:41:20 GMT
References: <6566@cs.Buffalo.EDU> <29060@cornell.UUCP>
Reply-To: akm@drizzle.UUCP (Anant Kartik Mithal)
Organization: University of Oregon, Computer Science, Eugene OR
Lines: 44

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



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Anant Kartik Mithal					akm@cs.uoregon.edu
Department of Computer Science				akm@oregon.BITNET
University of Oregon					akm@drizzle.UUCP