# Re: [K12OSN] electricity use

• From: Olle Niit <olle paalalinn com>
• To: "Support list for open source software in schools." <k12osn redhat com>
• Subject: Re: [K12OSN] electricity use
• Date: Wed, 14 Mar 2007 08:55:21 +0200

```It's not a right calculation at all.

I have server at homeoffice with 500w power supply.
It's AMD Sempron 3000+ socket 754
ram 512MB DDR400
NEC DVD-RW
HDD 400GB ATA100 and HDD 400GB  SATA software mirroring
2 netcards ( 1 onoard and 1 extra)
1 extra cooling fan for HDD-s
Linux E-Smith 7.5
```
I have APC PackUPS RS800, it tells that average power required is 51Watts. Maximum I ever seen was 61watts, and at start time 71Watts.
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But - Once upon a time there was some kind of Compaq or NEC monitors, whitch required at sleeping time very mutch power ( funny that they wasn't explosed). There was central APC 5000VA ups, and when all computers was tutned off, ups shows very many amps load currency. And when we pluged out monitor cords - load was 0 AMPS again. Those monitors was totally killers. I never seen it before or after. But there was one seria of 15" CRT monitors - even when monitor was sleeping and yellow led was turned on - power they needed was allmost like some kind of working heaters.
```

Robert Arkiletian wrote:
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I am not an electrician but I do teach basic electric circuits in
physics. The basic equation for power is P=IV (Power=VoltagexCurrent)
So 120 Volts (which is a north american standard) x 20 A of current
equals 2400 Watts of power.  Now if you remember those old boxes
probably have 200W power supplies max + monitor ~75W. Add another 25
for safety. So I would say 300W/box is reasonable. Although less would
probably work because I doubt they would draw the max of the PS unit.
So with a 20A circuit (2400W) that equals 8 machines working at full
tilt.

```
Now compare that to an ebox 2300 + and a 19in lcd monitor consumes. 15W + 40W
```Plus the server, don't forget.
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--
Olle Niit
Teknet Arvutid OÜ
tel 53 767 888
olle teknet ee

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