Recently I bought a power device for measuring the real power needed by a computer.
I put this measuring device just between the computers power cable and the power plugin in the wall.

After some days of measuring I was really surprised.

My computer (AMD Athlon XP 64 + PCIexpress) need on average 82 Watt!
Maximum during these days was 112 Watt.

So why do I need a 350 power supply unit in my computer?
Moreover 350W - 400W seems to be the standard.

When one take into account that the power supply unit operates most efficently only
when its is near to full capacity then it seems to me that all these 350W power supply units
are completely oversized.

150W would be sufficient.

All these gamers which run a high level video/graphic cards could buy a 400W PSU.

But for the "normal" office user this is bull shit.

Am I right ? Or what is the reason for these high capacity PSU ?

Jason

jjstacy (AT) yahoo (DOT) net (Jason Stacy) writes:
Maybe you don't. But if you expand your conputer, you might.

That is not generally true. Looking at the power supply test in c't
24/2006, I see that the tested power supplies have 71%-83% efficiency
at 20% load, 76%-86% efficiency at 50% load, and 72%-82% at full load.

If you strive for efficiency, it's more important to get an efficient
power supply than one that is more than 50% loaded. BTW, if you shop
around for a new power supply (especially a tightly sized one), look
up at which voltage your motherboard consumes the most power, and
check how much power the PSU can deliver at that voltage.

Maybe. A few stories:

- We recently bought a Dual-Xeon server. Our vendor could not get it
to boot with a 600W (IIRC) power supply, so this machine got an 800W
PSU. The highest power consumption that we measured on this machine
is 423W.

- My computer has a 350W power supply, like yours. It used to consume
up to 180W, and its PSU was sufficient for that. So for your 112W,
you probably can use something smaller, if you can get it.

- Several years ago a friend of mine bought a broken Elitegroup
motherboard for an Athlon or Duron system. He's the kind of person
who never does returns; instead, he tinkered around with various
combinations of CPUs, RAMs, and PSUs, and he did get this board to
run with exactly one PSU, a ridiculously small one (IIRC 125W); with
the stronger power supplies it failed.

Followups set to comp.os.linux.hardware

- anton
--
M. Anton Ertl Some things have to be seen to be believed
anton (AT) mips (DOT) complang.tuwien.ac.at Most things have to be believed to be seen
http://www.complang.tuwien.ac.at/anton/home.html

"Jason Stacy" <jjstacy (AT) yahoo (DOT) net> a écrit dans le message de news:
45f8476c$0$6403$9b4e6d93 (AT) newsspool2 (DOT) arcor-online.net

Does your device measure correctly peak power?

When you have your computer freezes because you plugged a USB device, you'll
reconsider that question.

The reason is very simple: you don't want to change the PSU every time you
make an extension. The same way you don't want to call your electricity
company each time you want to switch on both the oven and the washing
machine.

--
~~~~ clmasse on free F-country
Free technical support at : http://www.protonic.com/

"Cl.Massé" <retour (AT) contactprospect (DOT) com> wrote

Notice on the bathroom mirror of a holiday villa in the Tuscan mountains of
Italy:

"If you must plug in a hairdryer - unplug the fridge first".