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Low-end PSUs always dissipate the max rated power?

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Anonymous
a b à CPUs
a b ) Power supply
June 3, 2005 4:32:37 PM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Hello everyone,

I'm rather confused over something I was told today.

Low-end PC power supply units always dissipate whatever power they are
rated for, e.g. a 400W PSU will always dissipate 400W whether the system
is idle or not. If the system does not need the power, then that power
is dissipated as heat (?!?). That would make the power saving features
on modern CPUs almost moot, no?

Is it true? Are PSUs, even cheap ones, able to provide whatever power is
needed up to the limit, or do they always crank out the max?

--
Regards, Grumble
Anonymous
a b à CPUs
a b ) Power supply
June 3, 2005 5:49:27 PM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Fri, 03 Jun 2005 12:32:37 +0200, Grumble <devnull@kma.eu.org> wrote:

>Hello everyone,
>
>I'm rather confused over something I was told today.
>
>Low-end PC power supply units always dissipate whatever power they are
>rated for, e.g. a 400W PSU will always dissipate 400W whether the system
>is idle or not. If the system does not need the power, then that power
>is dissipated as heat (?!?). That would make the power saving features
>on modern CPUs almost moot, no?
>
>Is it true? Are PSUs, even cheap ones, able to provide whatever power is
>needed up to the limit, or do they always crank out the max?

What nitwit told you that? A salesdroid at Best-Buy?
June 4, 2005 2:41:09 AM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Fri, 03 Jun 2005 13:49:27 -0400, daytripper wrote:

> On Fri, 03 Jun 2005 12:32:37 +0200, Grumble <devnull@kma.eu.org> wrote:
>
>>Hello everyone,
>>
>>I'm rather confused over something I was told today.
>>
>>Low-end PC power supply units always dissipate whatever power they are
>>rated for, e.g. a 400W PSU will always dissipate 400W whether the system
>>is idle or not. If the system does not need the power, then that power
>>is dissipated as heat (?!?). That would make the power saving features
>>on modern CPUs almost moot, no?
>>
>>Is it true? Are PSUs, even cheap ones, able to provide whatever power is
>>needed up to the limit, or do they always crank out the max?
>
> What nitwit told you that?

The guy selling 400W zener diodes.

> A salesdroid at Best-Buy?

Even they know where the awning is when it rains.

--
Keith
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Anonymous
a b à CPUs
a b ) Power supply
June 4, 2005 11:02:07 AM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Grumble wrote:

> I'm rather confused over something I was told today.
>
> Low-end PC power supply units always dissipate whatever
> power they are rated for, e.g. a 400W PSU will always
> dissipate 400W whether the system is idle or not. If
> the system does not need the power, then that power
> is dissipated as heat (?!?).

The person who told that to you had absolutely no understanding of how
power supplies work because if it were true, then supplies would be
hottest at zero load. Try simulating this by installing lightbulbs
totalling 400W in a small ventilated metal box with a fan blowing air
through it, an it should become unbearably hot in a few minutes. Even
linear supplies, which regulate voltage by intentionally turning
unneeded power into heat (essentially like regulating the speed of the
car through the brakes), don't get hotter at lower loads. For an
explanation of how computer supplies work, try
http://computer.howstuffworks.com/power-supply.htm

Cheap and expensive computer supplies operate basically the same way,
only the cheap ones usually don't work as well (can't put out as much
power, voltages regulated worse, overload protection fails), major
exceptions being those from Fortron-Source, which are among the best
but often also among the cheapest.
Anonymous
a b à CPUs
a b ) Power supply
June 5, 2005 5:12:49 AM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Fri, 03 Jun 2005 12:32:37 +0200, Grumble <devnull@kma.eu.org> wrote:

>Hello everyone,
>
>I'm rather confused over something I was told today.
>
>Low-end PC power supply units always dissipate whatever power they are
>rated for, e.g. a 400W PSU will always dissipate 400W whether the system
>is idle or not. If the system does not need the power, then that power
>is dissipated as heat (?!?). That would make the power saving features
>on modern CPUs almost moot, no?
>
>Is it true? Are PSUs, even cheap ones, able to provide whatever power is
>needed up to the limit, or do they always crank out the max?

Don't tell us.... this guy has a tube amplifier in his home theater
system?:-)

--
Rgds, George Macdonald
Anonymous
a b à CPUs
a b ) Power supply
June 6, 2005 12:49:17 AM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Haven't been able to find any "cheap" Fortron PS's over 400W anywhere.

<do_not_spam_me@my-deja.com> wrote in message
news:1117890297.469900.269470@f14g2000cwb.googlegroups.com...
>
>
> Grumble wrote:
>
> > I'm rather confused over something I was told today.
> >
> > Low-end PC power supply units always dissipate whatever
> > power they are rated for, e.g. a 400W PSU will always
> > dissipate 400W whether the system is idle or not. If
> > the system does not need the power, then that power
> > is dissipated as heat (?!?).
>
> The person who told that to you had absolutely no understanding of how
> power supplies work because if it were true, then supplies would be
> hottest at zero load. Try simulating this by installing lightbulbs
> totalling 400W in a small ventilated metal box with a fan blowing air
> through it, an it should become unbearably hot in a few minutes. Even
> linear supplies, which regulate voltage by intentionally turning
> unneeded power into heat (essentially like regulating the speed of the
> car through the brakes), don't get hotter at lower loads. For an
> explanation of how computer supplies work, try
> http://computer.howstuffworks.com/power-supply.htm
>
> Cheap and expensive computer supplies operate basically the same way,
> only the cheap ones usually don't work as well (can't put out as much
> power, voltages regulated worse, overload protection fails), major
> exceptions being those from Fortron-Source, which are among the best
> but often also among the cheapest.
>
Anonymous
a b à CPUs
a b ) Power supply
June 8, 2005 3:14:40 PM

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

dawg wrote:

> Haven't been able to find any "cheap" Fortron PS's over 400W anywhere.

They're relatively cheap, but a 350W Fortron will usually put out as
much as a typical major brand 400W.
!