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Old 2003-12-03, 05:48   #1
optim
 
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Default Power consumption

I have an 800VA (480W) UPS installed on my machine. I used UPS software to calculate the power consumption of a PC running Prime95.

When I don't run Prime95, my UPS is 36% loaded = 172W.

But when I run Prime95, my UPS is 43% loaded = 206W.

206W - 172W = 34W.

My machine is an overclocked AMD Athlon XP "Barton" 2600+ @ 2.125GHz with 1GB main memory, 3 hard disks, 425W power supply unit and 19" CRT monitor.

The reason the computer needs the additional 34W when running Prime95 is the CPU: Prime95 uses the CPU at its full capacity, so the CPU takes more power during its operation. It doesn't matter whether you run Prime95 or a game: Whenever the CPU usage is 100% it gets more power than usual.

So we can say that Prime95 on a modern AMD CPU takes the power of a small light bulb :)

From the above test I understand that a 425W power supply doesn't take 425W all the time from the wall socket. It takes only the power it needs. Am I right? Is this (UPS and software) a good way to calculate how much power is being used by a PC?
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Old 2003-12-03, 08:45   #2
Maybeso
 
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Does your system have any variable speed fans, either on the case or on the cpu cooling unit?

You should split that 34W between Prime95 and the extra cooling needed.

When I pause prime95 before doing a backup or defrag, the fan changing pitch sounds like my PC is sighing in relief.
Phew! Gimme a sec, gotta catch my breath!
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Old 2003-12-03, 09:01   #3
optim
 
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I hadn't thought about that. I just checked it and you are right

my CPU fan falls down from 4200RPM to 3700RPM when I pause Prime95!

Last fiddled with by optim on 2003-12-03 at 09:02
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Old 2003-12-04, 11:00   #4
TauCeti
 
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Default Re: Power consumption

Quote:
Originally posted by optim

So we can say that Prime95 on a modern AMD CPU takes the power of a small light bulb :)
My P4-System (about 3 GHz) is using an additional 40W doing Trial Factoring and 63W doing LL-Tests compared to idle-mode.
And those 63W are without overhead (no UPS and steady fan-speeds)...

It would not surprise me if prime95 may be one of the reasons for the delay of the new P4 prescott-core until 2004-02-02.
AFAIK Intel uses prime95 for testing purposes
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Old 2003-12-04, 23:08   #5
E_tron
 
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Prime95 has no effect on a VIA EPIA 800mhz processor , however it performs like a celeron.
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Old 2003-12-04, 23:10   #6
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optim. Did you calculate power consumption with a monitor or without?

I must know .
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Old 2003-12-05, 00:27   #7
QuintLeo
 
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Those figures seem a little high - but you may have more "stuff" in your machine than I do in my Athlons.

I don't know how accurate your UPS power monitoring capabilities are - they seem to be in the right ballpark, though.

Personally, I've got a Brand 1850 power meter to do my power checking with - it's got Power Factor calculation and other such needfull stuff built-in. 8-)
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Old 2003-12-06, 03:01   #8
optim
 
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During the test the monitor was on. The monitor is a Vibrant VM92 19" CRT.

The UPS software I used is Commander Pro. The UPS itself is a SmartCentra 800VA.

Last fiddled with by optim on 2003-12-06 at 03:03
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Old 2003-12-06, 04:13   #9
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Ah - with monitor, those power figures look a LOT more reasonable.

My Thoroughbred 1800 box (actual clock at 1850) runs about 145 watts with Prime running, but that doesn't count the monitor or anything else but what's in the CPU's box itself.
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