PC Power Consumption

[XS650]

I've been using a Kill-A-Watt Watt meter on various things for some time now and decided to take a look at PC power consumption as I changed some things.

The only change I made that is cost effective to make was my LCD monitor brightness. Some changes I made to the PC itself helped a lot but generally wouldn't pay for their selves unless you needed to buy the components for other reasons.

My monitor is a 21 inch Samsung 214T LCD. I was running it at 100 brightness on a scale of 0 to 100 on the control panel. 100 is real bright, 0 is usable but dim.

Monitor power consumption at 100 on the control panel was 55 Watts. I cut the brightness down until it was a bit too dim then cranked it up a bit until it looked good to me. I ended up on 60 on the scale which was 37 Watts on the Wattmeter. A 33% savings for free.

I got started on this because I was getting occasional non-starts on the computer where it would beep out an undocumented POST code, then shut off. Indications per web wisdom were that it was a power supply problem. I finally broke down and bought a power supply and it fixed the problem.

The computer had idled right at 100 Watts with the Antec 380 Watt power supply that was in it. It was at 100 Watts long before I started having problems, so I think the problems have nothing to do with these numbers.

I got a Seasonic 80%+ efficient 430 Watt power supply. The curve showed it at over 80% efficiency down to low power levels.

Installing the new power supply with no other changes cut idle power consumption to 75 Watts, a 25% savings.

At that point I decided my 3 year old AMD 64 3500+ in an Abit AV8 motherboard was worth a little work for a few more years use. It had always been a bit noisy. The last noise problem was a noisy fan on the video card so I upgraded the GPU cooler to a Zelman with a big heat sink and slow quiet fan. It worked like a champ and the fan was silent, unfortunately the universal mount allowed the fan mount to shift slightly and short out against a small capacitor on the video card resulting in a dead video card. Bummer.

Another trip to Frys....

I found another Nvidia based video card with about the same specs as mine except now, 2 years after I bought the other card, that level of performance doesn't require a fan.

With then new video card, computer power consumption dropped for 75 Watts to 62 Watts at idle.

The computer uses PC3200 memory which is becoming obsolete and already costs more than PC6400 memory. With memory prices projected to increase, I decided now was the time to upgrade to 2 GB of RAM. My old 1 GB of RAM wasn't usable with anothe 1 GB because of motherboard configuration,so I bought 2 GB new. Surprise, the new 2 GB of Ram dropped computer pwoer to 58 Watts. Both batches of RAM were middle of the road Patriot Ram, they must be getting more efficient to run twice the RAM on less power.

End Result, computer plus monitor power consumption reduced from 155 watts to 95 Watts, a 39% savings.

I have also noticed that with the PC running Linux it uses 4 fewer watts than running XP. The Linux power savings wasn't included in the above numbers.

 

[Volvohead]

Seasonic makes a solid PS. While PCP&C units are more robust, Seasonic is right there for stability, and they are very efficient. Antecs are garish junk AFAIK.

We have a AV8 with a 3500 newcastle around here on one system. A 430 watt box might be a little under spec. Higher end video cards draw heavy amps under load. I don't look at anything under 650 nowadays.

 

[obbop]

By gosh, that was an interesting report on the progressive decrease in power usage and the methods used to obtain said savings.

And people say Coot has too much time on hand when sharing the shanty's wonders.

I scoff. Coot snorts in derision.

Let the lackluster lowbrows infesting the least common denominator dwell within their demented demeanor.

I, for one, will revel in reports such as the one a couple stories above. And, Coot may just wait until the gnarly clammy clutches of winter strike and present a montage of images of a shanty and occupant braving the arctic air, fending off death day-by-day, a mere matter of hours lying between coot and a frozen Coot.

Something like that.

Hey!!! Anyway to convert the watts to mpg's???

 

[XS650]

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Seasonic makes a solid PS. While PCP&C units are more robust, Seasonic is right there for stability, and they are very efficient. Antecs are garish junk AFAIK.

We have a AV8 with a 3500 newcastle around here on one system. A 430 watt box might be a little under spec. Higher end video cards draw heavy amps under load. I don't look at anything under 650 nowadays.

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You're mot the only one I've run across with that opinion of Antec power supplies. At least mine worked with no problems for 2 years.

Fortunately (or not, depending on your viewpoint) I don't have have a high end video card. It's an Nvidia chipped e-GeForce 6200.

Since my computer draws about 50 Watts doing nothing and 110 Watts spinning a 3d topo map around with the cpu running at a steady 100%, how would I determine what capacity power supply I need?

 

[Volvohead]

Bear in mind this little appreciated fact. The most important part of a computer system is not the MB, nor the CPU, memory, HDD, or any other peripheral. It's the power supply. It all starts there, and many later "hardware problems" often originate or are traced to power supply irregularities and failures.

I've probably rolled over 50 systems and diagnosed several times that. Take my word for it: investing in a decent power supply is one of the best things you can do if you're a systems builder. The PS form factors are fairly stable, should remain so for the foreseeable future, and a good PS, selected with some capacity overhead (always buy more than you "need"), can last over several systems.

 

[XS650]

Quote:

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Bear in mind this little appreciated fact. The most important part of a computer system is not the MB, nor the CPU, memory, HDD, or any other peripheral. It's the power supply. It all starts there, and many later "hardware problems" often originate or are traced to power supply irregularities and failures.

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I am slowly, painfully gaining an appreciation for that.

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I've probably rolled over 50 systems and diagnosed several times that. Take my word for it: investing in a decent power supply is one of the best things you can do if you're a systems builder. The PS form factors are fairly stable, should remain so for the foreseeable future, and a good PS, selected with some capacity overhead (always buy more than you "need"), can last over several systems.

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So, how do you determine how much power a computer needs, then how much reserve on top of that?

 

[Volvohead]

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So, how do you determine how much power a computer needs, then how much reserve on top of that?

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Today, there are some online tools such as:

http://www.extreme.outervision.com/psucalculator.jsp

Years ago, we had to sit down with all the component data sheets and calculate out the numbers.

The standard rule of thumb is to build in a 20-30% margin. But I always try to build in a 50% or higher margin, which will cover PS wear and tear (supplies weaken over time and that rate is accelerated by heavier sustained loads, i.e. undersizing), upgrades, AND ALSO one or two new system builds in the same CPU generation. A 750 watt supply using 200 watts is still only using 200 watts. But the extra is there when you need it. And always buy quality.

That it costs more upfront is usually more than covered down the road.

Occasionally, you get a PS that really shines. We've got a higher end 400+ watt PCP&C supply that is nearly 10 years old, that started life in a K6-III system and is now still going strong 24/7 in a later Athlon XP system. It was far cheaper in the end than buying three or four (or more) Antecs over the same period.

The importance of the power supply is somewhat of a universal across electronics. Old hands into audio equipment have long appreciated that value.

 

[Virtuoso]

I wouldn't put Antec's in the junk catergory. I have a nice Antec TrueBlue 480w unit that's treated me nicely, and the other unit's I've had have performed very well for years. One is on it's sixth year and no hiccups. I guess you get a bad apple every now and then.

You want to see a junk power supply? Check out the ones that come supplied with the $40-60 cases..

 

[XS650]

Volvohead, thanks for the link. I says I need a 275 Watt PS, so my latest high quality 430 Watt is plenty.

Quote:

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A 750 watt supply using 200 watts is still only using 200 watts. But the extra is there when you need it. And always buy quality.

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A 750 Watt power supply "delivering" 200
watts will use more power than a 400 Watt power supply delivering 200 Watts. In some case, quite a bit more. All else being equal, the high Wattage power supply will be further off it's efficiency curve peak.

 

[Master ACiD]

i have a gig of ram, athlon xp 2200+ at 266mhz fsb. ati radeon video card with dual out, 2 optical drives, 2 hard drives, a network card, audio, etc etc etc and my system only takes 98 watts to run sitting here at the desktop. if i jump into a video game it goes up to 125. i am using a 12 year old gateway power supply salvaged out from behind a gateway store when they closed down.
my dual 19 inch widescreen lcd monitors take about 36 watts a pop to run.
thats 2 lightbulbs to have a running computer folks.

the recent explosion on power supply wattage is only a temporary spike. expect to see computers touted as energy efficent in the future. i bet they start using laptop processors which adjustable clock ratios and voltages to lower power requirements. personally i wouldnt own a computer that took over $300 watts to run, exclusing temporary items like sound and printing of course.

 

[Volvohead]

You're correct. I should have been more precise in my choice of words. No PS uses exactly the power it delivers; no PS is 100% efficient. I meant to say "delivers" with respect to wattage, but was in a hurry.

However, delivering below the "efficiency peak" is not necessarily such a bad thing, as absolute numbers still tend to be better. And less overall heat from operating more watts under capacity is ALWAYS better.

 

[unDummy]

I'm glad that someone has brought up power wasted by computers.

I can't convince the company I work for to remove screen savers and simply shut off the monitors(not LCDs). Thats 200 monitors and computers(that never standby or hibernate). And, all they do is cry about the budget. We only work 40hrs a week. The machines run 24/7.

I believe it was the electric company years ago promoting all the 'leave everything on always' mentality still active today. I wonder how much money they made on it!

I've convinced most of my coworkers/friends to use the switches, use flourescents bulbs, and to power up their home computers only when needed. Its just too easy to save power and $$$ by simply shutting something off when not in use.

Since overclocking, overvolting, and over powering is pretty common, many don't ever consider the 'opposite'. I've underclocked and undervolted various processors for power savings. And, most CPUs will tolerate a tad less voltage even when running stock speeds. Not only will it use less power, it will run cooler(if CPU cooler fan is variable it will speed up less often).

To determine the power supply that you need, all you need to do is add up ALL the power ratings of each component. Your power supply should be able to provide the total amount required. Sure, the odds are you will never have everything working at 100%, but you also don't want the power supply running 'all out' always either.

BTW, I'm typing this on a computer using a 250 watt power supply. And, various customer builds only required 300-350 power supplys. The 430-watter you have should be plenty.

You can run CPU-z to see which Athlon core you have. There are several AMD 3500's. Once you have the info, search online if it is a good overclocker. If so, it could be a good undervolter at stock speeds.

You should also check for the lastest BIOS. My most recent bios update reduced north/southbridge temperature. Either the software is more efficient, or they changed the power needed for usuage.

 

[Volvohead]

I don't necessary subscribe to the philosophy of "on only when used" with hotter running microelectronic equipment, particularly with the more expensive varieties. Electricity is only one consideration in the overall cost equation.

While it does save energy, my experience is that equipment is more failure prone with repeated cycling. This is not just from the electrical surges that occur when energizing the equipment, but also from the mechanical effects of repeated thermal cycling. It's no coincidence that most hardware failures arise during power up.

On a $400 Dell disposable with unimportant data aboard, it might make sense to turn it off and on all the time. But on a more expensive custom or high end workstation, data server, or anywhere where system down time has significant value, 24/7 is cheaper, all things considered. Tech time and parts are more expensive than kilowatts.

Still, I'm all for a high efficiency PS, as they do lower average operating temps and save some energy.