The 100W AMD/Intel PC - small server build log - Overclock.net

dragosmp · 06-27-08

This thread is about the power consumed by each component in a PC.

Silent computing can be achieved in my opinion in two ways: either optimizing the airflow to minimize turbulences, or to lower the consumption of the PC so that the airflow can be reduced.

My purpose is to build a 100W PC, but since VIA's CPUs are weak, ATOM is just as bad, I've got to the point of considering classic PC components with a twist. The thing is all will be powered by a laptop plug + an ATX adapter.

The details of the PSU for this 100W PC are in this thread. Mootsfox and shinji2k pointed out a PC can actually be powered by a laptop plug if using an 12V-to-ATX adapter. These adapters can apparently output up to 150W, so there are choices.

Now how much each component consumes? I have taken two sources for my estimations: www.silentpcreview.com and http://extreme.outervision.com/PSUEngine

Silent PCR shows the idle/load power of HDDs, while the PSU calculator shows the power of all the system. By adding up and subtracting components I've isolated the consumption of each component.

Put the TDP and the system utilization at 100% to make the estimations reliable. For example: put a rig (whatever components) in the PSU calculator and look at the power needed. Add a 7200 rpm SATA HDD over whatever you have put before, and you'll notice that you need additional 24W => a sata hdd consumes 24W (according to them).

Using this principle the power of each component are the folowing:

- Midrange desktop mobo 38W
- HDD 24W
- DVD+-RW 27W
- 1x stick DDR2 4.5W
- usb 2W
- firewire 7w
- fan 120mm 4W
- fan 80mm 1w

The CPU wattage depends on what you want to use. I have chosen two examples:
- Athlon X2 4400 AM2 65nm @800MHz @0.85V 9W
- Phenom 9550 @1000MHz @1.0V 30W

I have underclocked both CPUs (using the OC CPU button actually) because there is little need of high-speed CPUs on low power media center PCs.

I further plan on sticking on AMD, here's why: 780G, nV8300 or 790GX aka hardware accelerated HD content. Intel doesn't have it, thus it can't possibly work with the CPUs underclocked.

Now there's the other side of the coin: silentPCR. They say a HDD consumes at most 12W, not 25W. The difference is too big to miss. For one I incline to agree with the silentPCR, as the HDDs don't get as hot as to suggest 25W of power consumption.

Would you like me help improve the specs? We will all profit from the added input on the consumption figures in the sense that we'll have a better idea of now much power it's needed for our rigs in all configs.

Cheers!

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*EDIT: Up to date values:

- µATX mobo 25W (figure from DuckieHo's 780G)
- 3.5" HDD 7200rpm 15W peak - 11W load (credit DuckieHo)
- 3.5" HDD 5400rpm 12W
- DVD+-RW 27W
- 1x stick DDR2 3.5 to 4.5W
- usb 2.5W (peak power - credit DuckieHo)
- firewire 7w
- fan 120mm 4W
- fan 80mm 1w

DuckieHo · 06-27-08

Corrected numbers for you:
AMD 780G = 25w loaded
Western Digital GP = ~12w spinup
Most other HD = ~15w spinup
1GB DDR2 = 3.5w

dragosmp · 06-27-08

Quote:

Originally Posted by DuckieHo

Corrected numbers for you:
AMD 780G = 25w loaded
Western Digital GP = ~12w spinup
Most other HD = ~15w spinup
1GB DDR2 = 3.5w

Thanks for the figures, they look closer to SPCR's point of view. +rep

*EDIT Could you point me to a source? Thanks.

DuckieHo · 06-27-08

Quote:

Originally Posted by dragosmp

Thanks for the figures, they look closer to SPCR's point of view. +rep

*EDIT Could you point me to a source? Thanks.

Note that my HD power consumption values are at SPIN-UP... when you first turn a machine on. During this time, your system isn't at 100% load. Actual power consumption when under load is more like 8-10w.

JBD1986 · 06-27-08

I'd have to assume that my rig is extremely eco-UNfirendly lol.

DuckieHo · 06-27-08

A USB channel can provide 5v@.5A. Therefore, the maximum power is 2.5w per USB port.

dragosmp · 06-27-08

Thanks for the USB figures also, I haven't thought of it like this.

As for the HDD data, it's normal that at spinup they suck the most power, but the PSU has to be big enough to power up the rig. I have checked the pico-atx PSUs and they can offer 110% their power for a couple of seconds, so the 10W figure may be the one that should be counted.

ryboto · 06-27-08

Under full CPU load, my system only draws 107W AC. If I were using integrated video, I'm sure the number would drop a little. I could reduce it by nearly 10W if I removed the Raptor and opted for a GP drive, or one of the new Samsung Eco drives.

dragosmp · 06-27-08

Quote:

Originally Posted by ryboto

Under full CPU load, my system only draws 107W AC. If I were using integrated video, I'm sure the number would drop a little. I could reduce it by nearly 10W if I removed the Raptor and opted for a GP drive, or one of the new Samsung Eco drives.

How did you measure this, if you don't mind asking?

If your numbers are true, than the whole concept can go down the drain

Manyak · 06-27-08

Excluding video card(s), a normal (1 CPU, 1 HDD, not overclocked) computer won't use more than 150W, maybe 250W if its top of the line stuff. And that's being generous.

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The 100W AMD/Intel PC - small server build log

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