Power consumption

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fireside 141 Sep 30, 2012 at 00:29

Don’t know if people here are into the hardware end of it, but I was wondering if anyone knew how much of a difference there would be in power consumption between an older amd desktop dual core 4200 with a dedicated video card, 21 inch monitor, compared to an amd laptop with a built in video card, 15.6 inch monitor. I know the 15.6 has a 60 watt power supply/charger thing. My desktop has a 350 watt power supply, but I don’t know how much of that is being used. Most of the time I just surf on it. Play games for an hour or so a day, but the computer is probably running 8 hours a day at least and I have a feeling is contributing quite a bit to my electric bill, which is fairly low, actually, but I’m kind of a nut about things like that.

edit: I guess what I’m wondering is if anyone switched from a desktop to a laptop and noticed a difference in their electric bill.

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Reedbeta 167 Sep 30, 2012 at 01:17

If you’re really interested in measuring your power usage, you might want to invest in one of these. They’re supposed to be pretty accurate, though I haven’t used one myself.

Googling around a bit I found people reporting 25-100 W for a desktop PC idling, depending on hardware loadout. For laptops it seems to be more like 10-15 W. If it’s on for 8 hours a day every day, that’s around 3 kWh/month for a laptop and anywhere from 6 to 24 kWh/month for a desktop. I don’t know about you, but that’s only a few percent of my electricity bill (total usage last month: 360 kWh).

My guess is appliances like your fridge, hot water heater, etc. make up a lot more of the power bill than the PC. Switching to a laptop could make a measurable difference, but not a large one.

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fireside 141 Sep 30, 2012 at 02:15

Hmm. That sounds like a disappointing amount of savings. I need to eventually buy a new computer, but I don’t think it should be high on the list for power savings. I’m going to think seriously about the Kill-a-watt. Thanks for the link.

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Stainless 151 Oct 01, 2012 at 09:13

Be aware that power saving “features” can be incredibly annoying.

I have just been bought a new mac book, dual booted with os X and win7

One of my builds is a really big project and takes 15 minutes to build, five minutes of that is really heavy work, both cores hit 100% usage.

When I first got the machine it kicked into power save mode after 10 minutes, totally screwing up the build and causing all sorts of damaged files to be created.

Took me a few hours to fix, and a few more hours to find the right setting to turn this “feature” off.

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fireside 141 Oct 01, 2012 at 16:34

I’ve always had desktops up to this point so it will be a new experience. Even some of the features on a desktop can be annoying, so I’m sure it will take some time getting used to a laptop. I want to eventually go off grid with a solar setup, which is why all these things are on my mind. I don’t know why, really, since my phone bill is higher than my electric bill, just the idea of it.

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TheNut 179 Oct 01, 2012 at 17:25

I tried the laptop route once. Hated the graphics chip, went back to custom building desktops at super low prices. Much better PPP (price per performance). Some hardware for the PC can reduce power consumption considerably. Enable the c-states for your CPU, avoid buying “cutting-edge” GPUs, buy green HDs (SSD if you can afford it), and take advantage of power savings in Windows. Some power saving features can be annoying at times (disable hard disks), but it does drop the consumption considerably. Putting your machine to sleep is also better than doing a hard boot if your sleep times are within a day or so. Toms Hardware has some specs of what certain hardware runs at. Intel chips are generally better then AMD in terms of wattage. You can cook food on most AMD CPUs. Most desktop CPUs tend to operate in the 80 - 130 watt under load, 30 - 50 watt idle. GPUs are by far the elephant in the room. Some cards can draw up to 350 watts. That leaves 50 watts left in my PSU!

I would be power conscientious for environmental reasons before my wallet, but often the two go hand in hand. Notebooks are good on power, but the lack of hardware diversity and ease of replacing parts is what turns me off. Had the laptop industry evolved like the desktop industry, I would have stopped buying PCs over a decade ago. Alas, such as it is, cheap hardware and cheap quality at expensive prices is a major turn off. For mobility and even doing Linux builds, I rely on my netbook. Like 5 watts on standby and with Linux console, there’s virtually no power draw even under use. I sometimes do long train rides (4-5 hours) and can almost coast the whole way without recharge. It’s not for everyone, but I love these little guys.

I wouldn’t bother to much on solar power. Most portable packages are gimmicks built with low quality. Better to spend $100 on another lithium battery to extend your use then spend $100+ on a portable solar unit with materials bought and constructed from the lowest bidder. A more versatile setup is to invest in portable battery chargers. They generally come with a high capacitance lithium battery that you precharge. You then plug your devices into it and it acts just like a normal power source until the battery runs dry. About the same in price as a laptop battery, but with more utility.

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fireside 141 Oct 01, 2012 at 18:54

Better to spend $100 on another lithium battery to extend your use then spend $100+ on a portable solar unit with materials bought and constructed from the lowest bidder. A more versatile setup is to invest in portable battery chargers.

I was talking about solar for my whole home. It’s really come down in price if a person uses a small amount of electricity like I do. I figure I can start out with a 300 watt system with 4 batteries (lead/acid). I plan on using propane for cooking. I burn wood and don’t use an air conditioner. I have a passive solar house which somewhat cools in the summer by storing night air and I live in Wisconsin. It wouldn’t be actually practical, but I would either break even or only lose a small amount in the long run.

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TheNut 179 Oct 01, 2012 at 23:41

I suppose if you wanted to be really disconnected, then maybe. I’m not sure if the benefits outweigh the costs. Home solar is tricky to setup because it’s inefficient to install panels on rooftops, especially if those panels don’t directly face the sun. You have to invest in a good mount to efficiently redirect the panels (helps if you have a flat roof). If that wasn’t a problem, then a single 300 watt panel with 100% efficiency for at least 2 hours would more than certainly power a laptop for the day. At 50% efficiency for 8 hours you can also have light to see your laptop and power an induction stovetop to eat a warm meal. Cut propane out of the equation.

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Reedbeta 167 Oct 02, 2012 at 02:08

I have a co-worker who installed solar panels on his roof. He has a flat roof and they’re just facing straight up, not tracking the sun or anything. Not sure how many panels he has, but he says he’s collected about 5500 kWh cumulative over the last six months. Averaged out, that’s over 900 kWh/month, which is quite a lot more than I for one typically use. And we’re in Seattle, which isn’t the sunniest of places.

On the other hand, those last six months did include summer. I don’t know how much power he’ll pick up in winter, but it’ll probably be at least a factor of 3 less than in summer, given our latitude. And if you heat your home with electricity then you of course need more power (my electricity usage is over 2x higher in winter). Overall, with his setup I think I could just barely pick up enough power to serve all my electricity needs throughout the year - if I had a way to store the excess energy from summer and use it the following winter. I don’t know if batteries can keep a charge for that long, though.

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fireside 141 Oct 02, 2012 at 07:41

With proper angle, I think the main difference is that there are a lot fewer hours of sunlight in the winter.  Usually about 10:00 till 3:00 for me, which is only 6 hours.  Using solar power for heat is kind of out unless you have a huge amount of panels, same with summer cooling.  Insulation is a much better investment and I’m in the process of adding more in my ceiling.  I’m going to only heat my downstairs, which is about 400 sq ft.  I have a pretty small house.  One of my biggest uses will probably be my refrigerator.  I’ve been tossing up using a 7 cu ft freezer with a cooler instead.  I think refrigerators were built backwards.  They should have a big freezer and a small refrigerator.  A 7 cu ft chest freezer uses less than half as much electricity as an 18 cu ft refrigerator, so I could also save by storing more garden vegetables, although using a cooler might be a little weird.  I was thinking of using blue ice from the freezer.  I mainly only put my yogurt in there anymore.  I don’t think it would be at all practical for a normal person, but I want to be more self sufficient.If you stay on the grid and the electric company allows it, you can turn back the meter and not require storage. Makes it a borderline good investment over the long haul.

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jph 101 Oct 02, 2012 at 23:24

if you add a small wind turbine (or small hydro system, if a stream is on site) to a solar setup you can be generating more continuously, as often when there is less sun there is more wind. I am planning an off grid home,. straw-bale, perhaps partially earth-sheltered,. I love the earth-ship idea, however I am more in the north, than the desert where they are perhaps more practice.

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fireside 141 Oct 03, 2012 at 00:17

Would be nice, but I don’t think I could afford both. I live in the woods with trees that are as much as 50 ft high, also, so building a tower would be a problem. I like reading and viewing videos on that stuff also, but my house is already built. I don’t see it as something that is 100 percent possible, but the more self sufficient the better. If I had to do without a few things in the coldest part of the winter, not that big of a deal. Microhomes are also interesting. I thought my house was small until I saw some of those.

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Stainless 151 Oct 03, 2012 at 08:18

Well, if you live in the woods, the single biggest power usage saving you can get is right on your doorstep.

Install wood burning stoves for heating, water heating, and cooking.

I grew up without central heating, a coal fire with a back boiler provided heat and water. An arga burned wood and coal for cooking,

Ok I got used to breaking the ice in the toilet bowl on winter mornings, and we had so many blankets on the bed movement was impossible, but the bills were cheap :D

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fireside 141 Oct 03, 2012 at 14:39

I burn wood for heating. I’m not sure I could afford to live like I do without it. I just trade stocks once in a while. I generally leave it cool off at night because I kind of like sleeping with lots of blankets. It gets a little dicey in January doing that, so I might leave a slow burning fire going.

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fireside 141 Oct 11, 2012 at 21:40

So, I got a kill-a-watt today. I was at Menards and it was on sale for 15 dollars. My Box uses about 100 watts most of the time, so everyone was pretty close. I think the monitor uses 40 but I’ll have to check that out. I’ll be able to monitor my average use this way also. Doesn’t sound like I can save a whole lot with a laptop. I have to wait for my electric bill because I don’t even know what the kilowatt hour rate is yet. Anyway, I got a fun new toy to play with that wasn’t too expensive.

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alphadog 101 Oct 12, 2012 at 15:39

I’ve used the KillAWatt to measure many desktops and laptops. In regular use, they take anywhere from 50-150W. At my rates, that’s about $5/mo. I’ve built lower-level systems consistently at about 30-50W use with good part selection, but they don’t have much video capability. Video (GPU+monitors) is the biggest power user, not really CPU.

In my case, I have three monitors and a big vidcard, so my carbon footprint is relatively-speaking “off the chizzain”.

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AliceLiddell 101 Oct 20, 2012 at 13:08

@fireside

So, I got a kill-a-watt today. I was at Menards and it was on sale for 15 dollars. My Box uses about 100 watts most of the time, so everyone was pretty close. I think the monitor uses 40 but I’ll have to check that out. I’ll be able to monitor my average use this way also. Doesn’t sound like I can save a whole lot with a laptop. I have to wait for my electric bill because I don’t even know what the kilowatt hour rate is yet. Anyway, I got a fun new toy to play with that wasn’t too expensive.

I was totally going to recommend measuring what your power consumption like that, I’ve done so in a Science class at a vocational school I used to attend. I’d recommend not worrying about what people think about solar powering your house and do it, also look into the haswell cpu next year if your interested in lowering your electric bill, just upgrade your cpu / mobo/ ram, and use the igp. You would be set and it would eat next to nothing. Upgrading from 939 to 1155 cost me $130 but I have 8gb of ddr3 and that was included in the price, your chipset dosen’t matter buy a really cheap one, and same with a budget cpu, my Celeron only eats 15 watts when I try to max it out. Also 32 nm is incredible even in a celeron I love knowing it costs next to nothing to have my computer on all the time.