Aprox. power usage?

[Drakantus]

I'm trying to estimate how much power is really used by all the computers in a rack, and I'm wondering if anyone has an idea as to what a typical 1u server uses. I am aware that usage and the computer specs vary, so I am just interested in an "average", or even a range.

Typical computer is a dell, with a single 1.4ghz pentium 3, used for fileservering. Any idea what kind of power usage this would require?

 

[ddrueding]

Used for fileserving? How many harddrives?

APC has a pretty cool power consumption calculator on their website.

 

[Drakantus]

Used for fileserving? How many harddrives?

APC has a pretty cool power consumption calculator on their website.

Most of them just have a single drive, not heavily used.

I think I see the calculator you are talking about, but it doesn't give me an estimated power usage, it just tells me which UPS I should buy.

 

[Fushigi]

Single or dual CPU? How heavily utilized?

I don't have the numbers offhand, but don't Xeon's burn upwards of 100 watts or more each? Throw in 11-18 watts per hard drive plus extra for the mobo (maybe 70 watts?) and the various fans.

I'd imaging a single-Xeon 1U server can pull 190-240 watts easy; upwats of 350 watts for a dual. And that's assuming 1 HD.

 

[Drakantus]

Thats exactly the info I was looking for, based on that I can estimate what they are using.

Thanks.

 

[Bozo]

I have two P4s running at 100% (folding). Each computer has 2 hard drives running. They are sharing a LCD display and keyboard/mouse.

My amprobe (ammeter) shows that together they are drawing ~5 Amps at 120V. They are both on the same outlet, with the monitor too.

A rough calculation would give 600 watts of electric being used. That's 300 watts each.

Bozo :mrgrn:

 

[i]

For $89.95, you won't have to estimate again.

 

[Mercutio]

A rough calculation would give 600 watts of electric being used. That's 300 watts each.

That seems like an awful lot for the sort of power supply that normally lives in a 1U machine. Is that a peak value or is it sustained?

 

[Pradeep]

Sounds like Bozo just has two desktop machines, using the same wall outlet.

 

[time]

Drakantus, the 1.4GHz was the last Pentium III and built on the smallest process. I'll hazard a wild guess that it can't draw more than about 60W. Even a P4 isn't especially hungry at that speed.

I'd estimate 100-150W per server (no monitor, and it's not realistic to expect a server CPU to be 100% utilized for extended periods). If pushed, 120W.

Bozo, 600W might be possible if the power supply efficiency is especially poor. What's the PS maximum power rating?

According to this really excellent article, a 3GHz P4 under full load requires 105W to the regulator. Adding 20W for two drives at idle and 40W (a generous guess) for the motherboard, RAM and graphics brings this up to 165W. Assume PS efficiency of 66% and your input requirement is 250W. Double it and add 50W for the LCD to reach 550W.

Opterons and Athlon 64's look pretty darn good to me, especially since you can still use Cool 'n Quiet on an A64 server (including Linux).

 

[Bozo]

Yes, it was two desktops on the same wall outlet.
Each pwer supply is rated at 400W

To estimate the size of a power supply that is needed, I use this: http://www.jscustompcs.com/power_supply/
It calculates 321W at full load. So my measured wattage is not far off.

Also, I forgot to include the speakers, cable modem, Linksys switch, printer, and VOIP switch are also on the same circut.

The idea was to give you a measured value rather than an estimate.

Bozo :mrgrn:

 

[time]

Power supplies only achieve rated efficiency at full load. Efficiency will be lower if you're only using less than half of the PS capacity.

Every online power supply calculator I have seen is utter rubbish. Ask yourself how the large PC vendors get by with such apparently low PS ratings. :-?

The idea was to give you a measured value rather than an estimate.

The trouble is, you didn't measure power, you measured current (or VA). Once you allow for power factor, your reading probably comes down to somewhere around 450W (assuming the ammeter is accurate ...). :wink:

 

[Bozo]

The current reading was taken at the outlet. It's the same as what the watthour meter sees and what my electric bill is based on.
Generally a poor or low power factor requires more power to do the same work. That's why power companies penalize customers with a low power factor.

Bozo :mrgrn:

 

[time]

You're sort of got it the wrong way around.

Here's both a simple explanation and a more complex one.

Your electricity company's meter measures true power, you're measuring Volt-Amps.