Re: 用 56 顆 AA 電池為 PC 供電 結 果只玩到 5 分鐘「踩地雷」就沒電了 - 電腦領域 HKEPC

On Thu, 3/5/2026 1:32 AM, Mr. Man-wai Chang wrote:
> On 3/5/2026 7:03 AM, Paul wrote:
>> On Wed, 3/4/2026 5:47 AM, Mr. Man-wai Chang wrote:
>>
>> It's the opposite. Modern systems have good idle power ratings.
>> Like mine draws 33W at idle, when driving a smaller-than-HD
>> resolution screen. And that's a system with a low end NVidia
>> card in it as well. The NVidia card was added because of a
>> crashing problem when using the iGPU.
>>
>> My first PC compatible, drew 150W at idle and 153W when
>> the single core CPU was railed. There was no power
>> ....
> 
> I surely have no data to support my wild guess about power requirement of old motherboards and CPUs. :)
> 

I only got the power meter, maybe 10 years ago, and to measure
the 440BX, that was done with a clamp-on AC ammeter.

The 150W measurement is not very accurate.

The power meter, uses a chip similar to the one that does
whole house digital power metering, about 1% accurate or so.
The measurement is done at the wall plug, the chip integrates
the area under curves and is capable of determine W and VA.
It can measure real and reactive power, and work out the
power factor PF. A power factor of 1.0 exists on ATX supplies
that have "active power factor correction". What that means
is, the power drawn is purely resistive (like an incandescent
bulb), there is no reactive (inductive or capacitive) power drawn.

For example, when the PC power supply makes +5VSB and the
computer is not really doing anything at all (this is NOT sleep),
the power meter measures this as 1W and 7VA. The local power
billing, charges for the 1 Watt. The 7VA is "reactive power"
and the power factor of the PSU is poor. The +5VSB portion
of the power supply, may not be using power factor correction,
which is why the reactive component (7VA or seven volt amperes)
is that high.

If I were to measure the 440BX computer again, I could use
that power meter, instead of the ammeter I used previously.
And then I would get a much more accurate measurement. The
ammeter has poor poor accuracy for this work.

But the message remains the same, that old computers are
generally bad citizens when it comes to wasting power.

The old computer, cannot even drive my 1920x1080 monitor. The
DACs on the video card, don't go that high. Which means if
I booted the 440BX into Windows 98, the screen would be
distorted and circles would be rendered as ellipses.
And back in the old days, the video card had two output
connectors, one might do 1152x864 , the other could do
1024x768 , so if you had dual-monitors, it could not
even do both of them at 1152. The second output used
a "cheaper" DAC.

   Paul