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Re: lower power PCs



On 30 May 2008 20:15:16 GMT, ddl@danlan.*com (Dan Lanciani) wrote in message
<1348321@xxxxxxxxxxxxxxxxxxx>:

>In article <s7tv34direo53ip0ks9t16bmv0o1r6t8h1@xxxxxxx>,
MFHult@xxxxxxxxxxxxxxxxxxxxx (Marc_F_Hult) writes:
>| According to this:
>| http://www.tomshardware.com/reviews/intel-cpu-power-consumption,1750.html
>
>Yikes, is he talking about 100+W for just the CPU?

Yes.

http://techreport.com/articles.x/7998/16 shows a graph of P4-generation CPU
power consumption. The P4's peaked out at about 160 watts/CPU.

[inserting from the original post:]

>I realize the "new" machine is a lot faster but I thought efficiency
>improvements had at least somewhat offset this.  Am I being unrealistic
>or should I be able to do better?

Over many generations of CPUs, power requirements have been reduced by a
factor of Vnew/Vold owing to lowering of CPU core voltages and reduced by
Lnew**2/Lold**2 owing to reduced die dimensions but that hasn't been enough
to prevent an increase in CPU power consumption in part because power use is
also roughly proportional to clock speed which increased almost 1000X since
the IBM's 8088-base PC.

Intel would assert that efficiency improvements have almost completely offset
energy increases in the context of a whole PC. It claims that since the days
of the 80286+287, the power requirement of PCs (not CPUs alone) has increased
only 4% (some would disagree with this) but the "performance" has increased
50,000%

http://www.sse.tulane.edu/Tef/Slides/Tulane-Moore's%20Law%20Sept02.ppt

>| the newest Intel Duo core CPU provide a "400% performance per watt
>|increase" compared to P4's.
>
>I wonder if that means I can have the same performance for 25% of the power.

Depends critically on how each processor is dedicated to tasks.

A good example would be video camera motion detection. You can use a PC to
convert the analog data from a video camera to digital and use an algorithm
to examine the data for changes that meet specified criteria. For multiple
cameras this requires substantial CPU resources which means lots of
transistor state changes each of which consumes power.

But you can use the "motion detected" CMOS/TTL contact closure (= ON/OFF;
1/0; "motion event") of the Samsung CV-MUX16TC video multiplexors that you,
BobbyG and I have, and cause this signal to 'wake up' a CPU or PC  to
increase video capture rate when actually needed. Power savings might be
1000X or more assuming that the multiplexor is going to be in use anyway (it
has its own significant power needs).

>At this rate I could run two of the older P3 machines for less power than
>the P4, and have lots more disks too.

Depends on what the computation load is on the CPUs. A sleeping P4 Computer
can use less power than a wide-wake PIII -- or PII or P or 286 or 8088.

And do look at your disk power requirements. I recently purchased a Seagate
7200.11 Barracuda 1 TB drive that idles at 8 watts (11 watts seek). This (I'd
guess) is 2-3X less than the original the 10MB fixed disk in the IBM PC/XT
and implies a 250,000-fold increase in performance/watt if performance is
measure by capacity.

Recent laptop drives typically use less than ~ one watt even at idle and ~4
watts full tilt.

So several, distributed, and (esp) smart PCs can use less power than a single
do-it-all HA PC. A distributed PC topology for a home automation system
shares some of the same advantages and disadvantages as a distributed vs
centralized security, thermostat, lighting control etc.

The 24 watts provided to powered devices by the proposed Power Over Ethernet
Plus (PoEPlus; IEEE 802.3at) will serve a both as a constraining  and
enabling technology for hard-wired, distributed PC's.

http://www.ieee802.org/3/minutes/mar08/0308_at_close_report.pdf

The current ~12 watt standard is too little for even low-powered mini-ITX
motherboards and systems. But 24 watts will be fine for many uses.

Here are a couple handy calculators to model power consumption of
custom/proposed mini-ITX and other PC systems.

http://www.epiacenter.com/powersim/powersim_v2/epiasimulator_v2.htm
http://resources.mini-box.com/online/powersimulator/powersimulator.html


HTH ... Marc

Marc_F_Hult
www.ECONtrol.org
Visit my Home Automation and Electronics Porch Sale at
www.ECOntrol.org/porchsale.htm


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