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Server Idle Power Consumption


WizADSL

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I'm curious to know what other people's unraid power consumption is when you server is at idle (awake with all drives spun down) with a CPU utilization of no more than 5%.  My consumption is about 120 watts under these conditions which seems VERY high to me.  I have checked the power consumption of the fans and they are not the issue.  The server specs are as follows:

 

8GB RAM

17 Drives

ASRock - FM2A85X Extreme6 Motherboard

AMD A10-6800K APU

80+ 850watt Power Supply (don't remember the make/model at the moment)

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I idle at ~60 watts when everything is set correctly (I had some recent issues with the pstate governor), typically 1 drive spun up for sharing media.

I have an i7-4790S (the lower power version)

500W 80+ PSU, 6 fans, 2 8GB sticks of ram,  typically 2 GPU's doing nothing, and an add on SATA card.

 

AMD's are typically not as efficient as Intel by comparison, however it seems they have gotten much better at this as of late.

 

Are you certain all "C" states are enabled in your BIOS?

How about reported frequencies for CPU, does it seem to be idling effectively?

 

I don't think that large of a PSU is doing you any favors, but I suppose it's better to have more than less.

 

Now keep in mind that the bigger wattage the PSU, typically the worse it does at lower wattage's, especially idle.

Since the efficiency is normally better at 30/50/80% of rated power draw.

 

So at 120 watts, you are at ~14% of rated load on the PSU, and are likely close to that 80% efficiency at that point.

Let's say 85% to be more conservative, so at 120 watts at the plug, your components are taking 102 watts to power, 18 watts wasted from efficiency losses.

 

Still seems a little high, but reasonable.

I'd be interested to hear what others experience with an AMD setup.

 

Is this done with a kill-a-watt, or some other meter?

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The system in my sig idles at about 35 -40 watts, based on a Kill-A-Watt reading at the AC outlet.  Yours does seems a little high.  Are all unneccessary motherboard features disabled?  Also, what version of unRAID are you running?  I seem to recall the AMD cpus having some issues with not throttling very well on Linux.  Might boot up a v6 beta just to see how much power it draws.

 

EDIT: Also, how are you connecting 17 drives?  Your SATA expansion cards probably make up the difference.

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The wattage measurement is with a kill-a-watt (there is a UPS in there as well, but I have compensated for it).  I am running unraid version 6.0.1.  The HDD controllers in use are 3 AOC-SASLP-MV8 (note NOT the AOC-SAS2LP-MV8).  The reason for the large PSU is that the case can support 24 drives so I though it best that I purchase a PSU that can handle it.  I was aware that PSUs can exhibit poor efficiency at low load but I didn't think that was the cause.  My guess is that it is more about AMD vs Intel which is why I wanted to find out what other people's values were.  I don't know if my BIOS settings are optimal but I will check (it's a bit of a hassle because the server is headless).  The CPUs do seem to be stepping down in speed based on the info shown on the dashboard page.

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My AMd machine (A10-7850K@4GHz), with drives spun down uses a little over 40W idle.    Under load it uses 140W+. 

 

It's about double the power of the Intel machine it replaces.

 

I can't say I'm impressed, and I'm thinking about returning it and going back to the Intel rig.

 

 

Each HBA will use about 5W, and each drive spinning again uses 5W.  So, with 3 HBAs, you're using close to 15W for those alone.

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Heres something to try but it involves tearing down your server to get to exactly what takes up the power.

 

I suspect its the Amd Cpu and the Extreme Motherboard. They are not known for power efficiency.

 

Shutdown the system.

Disconnect all drives from power plugs.

Disconnect all 3 hba from motherboard and power plugs.

Turn on system

Measure power

 

Optional step is using a seccondary usb thumb drive to boot from so your config wont get changed or altered at all.

 

Also, make sure you have the appropriate bios settings enabled to allow amd cpu to idle and step down speed and power.

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I found the Athlon 860K (which is basically the A10 I have minus the GPU) is much more efficient.  an 860K with a PCI graphics card would probably be more efficient than the A10.

 

I don't think the A10 shuts down the 8 GPU cores properly, so you're running the GPU needlessly all the time, which sucks power.

 

Something like an old PCI ATI RageXL uses less than 1W, and work with any board that has a PCI slot.

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