Naked Science Forum
Non Life Sciences => Geek Speak => Topic started by: paul.fr on 18/01/2008 22:42:05
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Assuming you only charge your laptop battery when you are using the laptop, are you then getting 'free energy' when running on the battery?
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power is lost when charging the battery, so laptops are less efficient.
Also, laptop technology is usually is more expensive than desktop stuff, if you want the same performance.
I've worked with people that have asked for laptops and never taken them out of the docking station...why?
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I'd say desktops are better. Not sure why. Just a hunch.
Maybe cuz when my laptop worked it was on 24/7 lol
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It depends what you mean by 'energy economical'.
As Turnipsock suggests, charging and discharging batteries loses energy (as we are discussing in another thread, it generates heat, and the generation of heat or sound is a direct indication of loss of energy).
On the other hand, part of the design criteria of laptops is that they should be able to run as long as possible on battery power (as long as possible turns out not to be very long at all once the batteries are of a certain age, but with new batteries, you should get a few hours work out of them with batteries). For this reason, there are all sorts of technologies that are used with laptops to try and minimise power consumption in other ways (reducing clock speed for less processor intensive applications, putting components to sleep when they have not been used for a while). All of these have a slight adverse impact on performance, but give longer battery life, and so are using less energy. These technologies could be implemented on desktops (some even are, but often the users disable them because they want maximum performance), but generally the criteria for desktops is geared more towards performance and less towards power saving.
So, in theory, you could make a desktop more energy efficient than a laptop; but given the market sectors the two types of machines are geared towards, in practice laptops are usually more energy efficient than desktops.
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OK, if we are going to look at how to build an energy efficient desktop (and as I build my own these days, so energy efficiency is one of the criteria, not only because I would rather reduce my energy costs, but because energy=heat, and I'm using the computers in a room that often gets hot in summer, so keeping them cool is important to me). I don't say I do everything to minimise energy - there are always trade-offs, but it is one factor I always keep in mind.
Firstly, if you can get hold of a processor that was designed for a laptop, and a motherboard that will suit that processor, so much the better. Not always easy, since most suppliers assume people are looking for raw performance, and not energy efficiency.
Secondly, on modern computers, that are often geared for games playing, the graphics card is going to consume far more energy that the actual processor. If you are not going to be playing games (and that is not what I buy computers for), then go for the slowest and simplest graphics card you can (many mother boards come with integrated graphics cards, and these will do file).
Likewise, don't buy the fastest processor, since speed=energy=heat. Think carefully what your processing needs actually are, and buy accordingly. For many applications, buying more memory will gain you more speed advantage than buying a faster processor. Also, a processor with a bigger on chip cache, but slower clock speed, will still be faster and more efficient for many applications.
Adding exta hard disks, etc. will also consume extra power, but less so than the processor or graphics cards, and they only consume power when they are actually in use, so simply having them in the box will not cost any significant power. The biggest problem with having extra hard disks, etc., is that even if you don't use them much, the power supply has to be rated to allow for the possibility that they will all be used at once. Then again, you can generally select hard disks that are more power efficient (but again, there is often a trade-off between power and performance).
Think carefully about the power supply you buy. If you are building a super duper computer with the latest and fastest graphics cards, and lots of other add ons, then you will need at least a 500W power supply, and that power supply will probably be rated at least 80% efficiency (so you could be losing 20% of the energy as heat) when at full load. The problem is the power supplies tend to be less efficient when at lower loads, so if you only need a 300W power supply (as most high end machines 5 years ago would have been rated at), then buying a 300W power supply to supply 300W is more efficient that buying a 500W power supply to supply 300W. On the other hand, buying too small a power supply can harm your machine, and at very least might shorten its life span - so it is a calculation you need to make carefully.
When you have put the machine together, there are a number of things you can change in the BIOS, or using utility programs, to improve its efficiency.
Firstly, most modern motherboards allow you to tweak the processor clock speeds and voltage to increase performance (and so consume more power), but some will allow you to tweak them to reduce performance (and so reduce power). Many of the modern ones can be quite clever, and adjust the processor speeds depending on the demands being made upon it, so the processor speeds up when you are doing something processor intensive and slows down when you are not.
There are also various other tweaks you can often do that (like laptops) will switch off components when not in use (e.g. the most common is to shut down the display if nothing has happened for 5 minutes).
Also, switching off the capability for wake on LAN, or wake on modem, or wake on keyboard, will all reduce power consumption when the machine is soft powered down.
What most laptops can do, but I have not seen a desktop do yet, is to save RAM to hard disk, and then totally power down when it it quiescent.
Oh, and one last point - don't use Microsoft Vista - Vista needs more memory, faster processor, and faster graphics cards than any previous version of Windows or than Linux, and all of this generates heat, and consumes energy.
And, ofcourse, if you are in an air conditioned building, and your computer is using more energy than it needs to, then it is generating more heat than it needs to, so the air conditioning is working harder to dissipate the heat, so you then have a second energy hit; first to generate the heat, and the second to get rid of it.
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Hello there,
Thank you for providing the A2A.
They claim that everything is relative. And it is also extremely related to this issue.
Desktops, in general, demand more power owing to bigger fans, CPUs, and GPUs.
But now comes the relative portion. When comparing an Acer Predator 21X laptop that requires two separate 330W power bricks to a respectable 450W desktop, the laptop consumes more electricity. But it is just a comparison of numbers. The amount of power drawn is determined by what is going on. A laptop running a game at maximum settings will use more power than a monster PC browsing the web or sitting idle. Needless to say, the identical desktop running a game would therefore use more power than the laptop. So everything is relative. The response will be determined by the comparison criteria you choose. However, when comparing a typical laptop and desktop, the laptop consumes less power.
I hope this was helpful!
Cheers!
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There is now increased awareness of the need for energy efficiency in computers (even before a war in Ukraine pushed up energy prices!).
Since the original post back in 2008, manufacturers have introduced a number of power-saving features, like:
- WInding back the clock frequency when the CPU isn't very busy
- Shutting down some CPU cores when they are idle
Despite the significant increase in CPU power and memory since 2008, power consumption has not increased in proportion.
But the most spectacular gains have been in mobile phones, which now have far more processing power, memory and communications, but, (with improved batteries) still manage to go a full day before needing a recharge.
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If my laptop's battery is run out, should I change it or buy a new desktop?
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If my laptop's battery is run out, should I change it or buy a new desktop?
Replacing the Laptop battery might be a Good idea.
You could check if the Laptop is still under Warranty, maybe that way you could get some discount.
Buying a Desktop will be Cool, but it will tie you up in a specific location.
P.S. - Welcome to the TNS Forum!
🙂
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Quite a good suggestion, thanks, I'll follow it!
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Quite a good suggestion, thanks, I'll follow it!
You're Welcome!
&
Welcome to the TNS Forum.
🙂
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I heard that desktops consume 10 times more energy than laptops.
Yes, the laptop should be recharged by a specific time period, but it is much better to use. You can work/study from everywhere.
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It depends on your occupation. For example, if you are a programmer, it will be better to have a desktop.
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Buy a 12v 400-600 watt 5 blade wind turbine with fixed tail fin, 600 watt hybrid charge controller (both 3 phase AC) , an 80 watt solar panel and two 40ah 12v sealed deep cycle batteries, and a pure sine wave 3000w constant (6000w surge) 12v inverter to your national power supply system bolts.
NB tower it around 20 feet up on a rigid pole.
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Yes, the efficiency of such systems is high, but the implementation process - one of the most difficult.