Is it worth building a low power computer?

ntavlas · Post by **ntavlas** » Tue Feb 12, 2008 3:33 am

Take a look at this thread, it`s rather interesting: viewtopic.php?t=42833

After reading this, I was wondering if it`s worth building a pc from parts when you want to achieve low power consumption.
Sure, there are some needs a laptop can not always satisfy such as gaming, raid storage and the pleasure of assembling your own machine.
But if you want a general use pc, laptops achieve some impressive power figures as low as 20 watts. A desktop computer would struggle to reach 30 and this is excluding the monitor!
Some of them are pretty quiet too, my mom's toshiba satellite for example works fanlessly when idle.

So much for pico psu`s and laptop hdds, maybe we should go for the real thing after all.

aaa · Post by **aaa** » Tue Feb 12, 2008 3:46 am

Well if you must buy new, a desktop would be cheaper.

Aside from performance that's the only advantage I can think of, power wise. Since this is Silent PC Review, a desktop has several advantages on that front (lots of space for bigger heatsinks and noise dampening),

AZBrandon · Post by **AZBrandon** » Tue Feb 12, 2008 4:19 am

I agree, if low power is the most important thing then laptops are close to impossible to beat. Like you said, 20 watts including the display is extremely low. I know my IBM Thinkpad shows only about 12 watts at idle when hooked to an external display. I can't even begin to think of how I would build a desktop computer with the computing power of my laptop and achieve a 12 watt idle. However, my desktop system is generally quieter than my laptop, especially once you start doing anything disk or CPU intensive. As with everything else, it is a trade-off. You do give up a number of things with a laptop that you can do with a desktop system.

nicke2323 · Post by **nicke2323** » Tue Feb 12, 2008 7:48 am

Some laptops can run fanless, but most don't. And when the fan runs, it's right under your nose.

I'm making the switch from a laptop to a desktop because I can't stand the noise anymore - even after undervolting and Speedfan tweaking.

ntavlas · Post by **ntavlas** » Tue Feb 12, 2008 10:09 am

Certainly, you have more control over the noise level of a desktop. But even though I`m pretty paranoid about noise, I have come across some laptops that many people in this forum could live with.
Unless I go for a gaming rig, my next computer will be a laptop.

Jay_S · Post by **Jay_S** » Tue Feb 12, 2008 8:09 pm

I've been thinking along these lines lately as well. Specifically, I need a low-power server for ftp and running slimserver. My current P3 server consumes about 40W at idle.

An asus Eee PC consumes about 15W, is more powerful, has a battery (quasi UPS), and most importantly to me, features three USB 2.0 jacks.

But really, there's no sense spending $300 to save $25/year in electricity. There's no cost parity for 12 years.

The two real benefits to me are the 2-3 hours of battery operation during power outages and USB 2.0 for external disks and backups.

Jay

aaa · Post by **aaa** » Tue Feb 12, 2008 9:02 pm

If you don't mind used you can find a laptop (with or without LCD depending on how old) for around 100-150. Considering the 9w idle I got out of my old P3-based E500, it should be interesting. I would recommend the bottom half of a Dell D600, those are very common and have undervoltable Pentium Ms.

frostedflakes · Post by **frostedflakes** » Tue Feb 12, 2008 9:13 pm

I used a laptop for a while as my main PC, they do make excellent low-power systems, and depending on the model they can be pretty quiet as well. The major downside to laptops IMO is that if something goes wrong, it can be a pain to find and replace the part. And the interoperability of desktop components seems more environmentally friendly to me. For example many desktop parts (especially cases) can be reused in future builds, whereas most everything in a laptop short of the CPU, RAM, and HDD can't be used in others models, meaning it'll probably end up in the dump.

ntavlas · Post by **ntavlas** » Wed Feb 13, 2008 4:16 am

Whether it is cost efficient or not depends on the math you use. Electricity here is more expensive, and 50$ per year over a course of 7 years (that`s for how long I`ve had my computer except the vga and hdd) negates the price premium of a notebook over a desktop. Plus you also get a small lcd screen and a "ups" for that money.
It can be a matter of principle too, using 50-80 watts just to surf the web seems silly to me.
By the way, it might be easier to reuse desktop components, but don`t forget that those components can weight up to 20 kg when most laptops are below 4 including their accessories..

scdr · Post by **scdr** » Wed Feb 13, 2008 11:50 am

Seems to me the first question is - why do you want to achieve low power consumption? Different tradeoffs are involved depending on which reasons are important, e.g.:

Is it because of limited power available (e.g. running on batteries, solar, human power). Only so many watts and/or watt-hours available.

Is it as a part of reducing overall environmental impact -
in which case you need to consider total life cycle impact.
Not just energy during use, but energy and materials during manufacture, recycling, and length of lifespan - durability/repairability/reuse/upgradeability, etc.
e.g. see portion of thread on green pc in green computing forum
viewtopic.php?t=46086

Is it because of cost? Again - total lifecycle considerations come into play.

Are you concerned about power (rate of energy use) or total energy used?
For instance doing video transcoding a machine that uses more power while on, but gets the job done sooner (and then turns itself off) may use less energy than one that uses lower power but for a longer time. (There was a thread about this not long ago.)

Some confuse low power consumption with high efficiency -
If what one really wants is high efficiency, then considerations of e.g. FLOPS/Watt come into play. (e.g. at folding, a Core2Duo quad core is pretty efficient, though it is not particularly low power.)

Desktops can also achieve high efficiency and/or low power consumption.
Consider e.g. the Mac Mini (Core2Duo).
(Added advantages - don't have to replace the monitor and keyboard when you upgrade.)

aaa · Post by **aaa** » Wed Feb 13, 2008 5:46 pm

scdr wrote:Desktops can also achieve high efficiency and/or low power consumption.
Consider e.g. the Mac Mini (Core2Duo).
(Added advantages - don't have to replace the monitor and keyboard when you upgrade.)

Tha Mac Mini is a laptop on the inside, it uses the mobile Core 2 Duo.