Where to get information about power consumption?



Hi, I’m here again with another of my… strange questions :bigsmile:

I’m trying to build a computer with two main main priorities: the lowest power consumption and the lowest noise production. I’m not planning to use this machine for video encoding or heavy gaming, so it’s not necessary the most powerful CPU or graphic card.

Browsing the net, I found an interesting solution: the new Intel Atom CPUs. According to the wikipedia, these processors are very low consuming.

There is a very interesting mainboard using these new CPUs, the Intel D945GCLF. This board seems a really promising one regarding the power consumption, but…

… but then I found this review

So is the Atom really low-power in practice? The processor is, yes. For the platform aimed at NetTop (low-cost desktop computers), the answer is yes, but… Why the “but”? Because the chipset used uses a lot of power and the processor is listed at a TDP of 4 W, compared to 2.4 W for the mobile versions. Our test motherboard consumes 59 W in standby, and we reached 62 W under maximum load (with a 3.5" hard disk and a 1 GB DDR2 DIMM). Obviously, these values are what we measured for the complete platform, not only the motherboard, and they don’t take power-supply losses into account (our test model has a yield of approximately 80%). That’s both a little and a lot – it’s not much for a desktop computer, of course, but it’s a lot in absolute terms. We should add that we recently tested a motherboard based on a 1.5 GHz Via C7, and the configuration drew less power with the same components: 49 W at idle and 59 W under load (always measured at the AC outlet).

Basically, these mini-ITX boards that are promising a very low power consumption are actually consuming a lot of power!!!

I was on the verge of buying the Intel D945GCLF board, but after reading the article at Tom’s hardware, I decided to not buy that board anymore because for the same price I can get a full ATX or micro-ATX board with integrated videocard that probably will have a lower power consumption.

My question is: there is a way to find the power consumption of a mainboard? I read many reviews, but this feature is never tested. It seems that for reviewers only the overclocking features are important to evaluate a mainboard :doh:

Browsing the wikipedia I was able to find that Intel Celeron 440 consumes only 35W, but these processors are not provided with energy saving features like latest 45nm CPUs currently available in the market. Because of 45 nm CPUs are for the most 65W processors, can I buy safely the Celeron 440 or the 45nm CPUs will guarantee me a lower power consumption?

According to this site, the Gigabyte GA G31M S2L is the “most energy-efficient performance available today”, but I’m not sure that this information is correct. There is no information about this at Gygabyte website.

Can someone suggest me a mainboard and a CPU to build a system with a very low power consumption? To reduce costs and to increase the energy-efficiency, a board with integrated video card is the preferred choice, also because it will be not necessary to have another fan spinning and producing noise. I will not use this board to watch movies, so it’s not needed a powerful graphic card.

Another advantage of the celeron 440 should be (if I’m not wrong) the possibility to cool the processor passively (remember that a silent PC is one of the main priorities).

Thanks everybody for suggestions :slight_smile:


You might look into building around the AMD Turion processor. The one in my laptop is an MT-37 (even has a 1mb L2 cache) and is rated at 25 watts and runs anywhere from 800mhz to 2ghz depending on the CPU load. It also drops the volt to 0.9 volts when idle or the CPU is running at 800mhz. Also, the Turion doesn’t need a separate memory controller like Intel’s CPUs and this makes them even more efficient. Independent memory controllers can really suck down the power.


One power waster is the PSU unfortunatley. A lot of new PSU’s are rated for 80-plus certification, but they don’t test these psu’s at low power consumption, so at 25%-100% consumption they are usually ~80% efficient, but below 25% consumption the efficient can drop off drastically. One solution is to build your own PSU, I think silentpcreivew had a project to make a ~90% efficient PSU that made around 100 watts. This is also a flaw in comparing those reviews of yours, because they are most likely using different psu’s and the efficiency will vary.

If you were to get this processor and under-clock it as well as under-volt it, you would lower the consumption quite a bit. Also use just one stick of ram, like 1gb for example. I would suggest to get a MB with onboard graphics like the geforece 6100/6150. Some older computers were super efficient, I fixed up an old Athlon xp 2GHz box and it idled using only 11W.


Here’s a cool article to read: Link

They are using the 690G video chipset which is higher quality video and uses more power. I don’t know how efficient the new 780G chipset is now.


Looks like from all the reviews that a 780G MB with an efficient cpu should ide using around 50W. Thats not underclocking the cpu or using one of those super efficient PSU’s.

Interesting thing in the above review, the cpu was far more efficient when using active cooling, like 14W under load was saved by using a fan that only draws around 1W.


Many thanks for answers :slight_smile:

I’ll have some more readings to do :flower:


I have a small HTPC setup running in a slimline case (1" tall) with 120W PSU and has the following in it

Gigabyte ATi 780G uATX motherboard
AMD X2 4200 ee processor, undervolted using RMCLock to limit power output
1TB WD Greenpower HDD
1GB 800MHz DDR2 ram
Slimline optical drive

It has no problems playing blue-ray and when using RMClock to undervolt the CPU to its lowest level it runs with just the case feeling slightly warmer than ambiant. Its currently working as a webserver / HTPC so is on 24/7 at less than 50W idle, max draw is under 90W at full load (possible 100W if you dont use RMClock to lower CPU voltage)


You might want to look at the Via Artigo system, full speed is 23 watts.


Thanks for information :slight_smile:

I’ll have a check :iagree:


Or fit-pc; 5 watts, but not very powerful.


Just checked: the Via Artigo has a fan. I wonder how noisy is it. Usually these little fan are very noisy (see the chipset fan for example)


Here is a good article on it.

Look here for low power fanless systems.



Wow! Thanks for the link, I’m really curious to read a review :iagree:


There is also the new Via Nano cpu, but I can’t find MB info. Via Nano