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[SOLVED] Disabling cores->save energy?

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November 16, 2011 3:31:00 AM

hello,
so my power bill has hit a new record, and im hoping to lower it a bit :/  i run a server at home from a dell optiplex 755 sff, which is pretty green to begin with. however, im really trying to cut back anywhere i can. im thinking about utilizing just 1 core of my cpu, an intel q6600 (2.4ghz quad core). the system runs ubuntu, so it doesnt really need all that much processing power to begin with, and my server doesnt really get tons of hits :p  despite that, will i be able to use less watts if i do this? oh, and specs are the following:
dell optiplex 755 slim form factor
2.4ghz intel core 2 quad q6600
2gb ddr2 ram
160gb hard drive@7200rpm
ati radeon hd 2400 xt (256mb)
ubuntu desktop 10.04

basically, i want to know if reducing my cores from 4 to 1 will save energy, and if so, how much?
a c 186 à CPUs
November 16, 2011 3:34:58 AM

Get a more power efficent power supply.
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a b à CPUs
November 16, 2011 3:45:10 AM

^ Yeah that's about the only thing you can do that won't cost too much. Further:

Look into greener cooling systems as well, water cooling and silent systems.

SSD's make a huge difference, as does slower HDD's (5400 RPM instead of 7200 RPM).

Less RAM chips (1 x 2GB uses less power than 2 x 1GB) can be considered.

The GPU is one of the most power-hungry systems on the board also, but yours is fairly weak. You can look into passive cooling if it's bothering you though (passive cooling basically means no fan on the heat sink).

Dropping cores won't really help, as it's the purpose of the server to have many to keep up with tasks.
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November 16, 2011 4:02:22 AM

What power supply do you currently have? If you have an 80-plus certified make, make sure it's gold certified. In addition, get a power supply that is capable of double the watts your system actually needs - this is where the efficiency peak occurs. If your system draws 180 watts of power (I'm just guessing), then get a 360-watt PSU (usually as 350, 375, or 400 - either will do). Gold-certified PSUs can get even 91% efficiency. Thus, if your system is drawing 180 watts, you're drawing 180/0.91 or 197.8 watts from the power grid and you pay for that 197.8. Run it for 5 hours and that's roughly 1 kilowatt. Over the course of a month, 731 hours roughly, that's 146 kilowatts. With some basic math like this, you find the power supply that best suits your needs to optimize your cost and electric bill, though focus more on the electric bill's cost as the savings will pay for the PSU itself quite fast with a gold-certified PSU considering that servers run 24/7.
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a b à CPUs
November 16, 2011 4:53:38 AM

Just enable speedstep and let windows do the power management. After all thats why you chose it as the OS to run your hardware
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a b à CPUs
November 16, 2011 5:09:00 AM

Don't disable cores, underclock.
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a c 84 à CPUs
November 16, 2011 5:29:35 AM

amdfangirl has it right. Find the lowest vcore you can use while being stable. If you don't need the processing power, underclock the CPU to a point where you feel comfortable with its processing power. Turning off cores in that CPU won't make much difference as they will still be receiving power. There isn't really any power gating in that chip.

I would take a look at a new PSU, but if you have a SFF case finding a new one might be hard. I'd also look at a new GPU. Might not draw a lot, but XT means it draws more then it should.
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a c 186 à CPUs
November 16, 2011 5:31:07 AM

OH yeah if possible use afterburner and underclock that radeon.
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a b à CPUs
November 16, 2011 5:41:42 AM

4745454b said:
amdfangirl has it right.


Of course!

/egotrip off
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November 16, 2011 6:15:30 AM

gnomio said:
Just enable speedstep and let windows do the power management. After all thats why you chose it as the OS to run your hardware


^+1

i dunno if ubuntu awares of speedstep or maybe there is a program to make it. Speedstep underclocks your proc automatically (based on the load).
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November 16, 2011 1:54:00 PM

amuffin said:
OH yeah if possible use afterburner and underclock that radeon.



Erm. doesn't your Optiplex 755 come with an onboard gpu? Just remove the Radeon and use the onboard.

As for changing the PSU, O doubt you would be able to fit a not Dell PSU in there.

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November 16, 2011 1:57:06 PM

Doesn't the Optiplex 755 come with an onboard display? Why not get rid of the Radeon, and use the onboard (might save a few there). As for the PSU, I doubt that you would be able to fit a non-Dell PSU in there.

PS: Apologies for the duplicate reply, Toms Forus are playing silly buggers again :-)
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November 16, 2011 6:24:02 PM

thanks for the replies everyone! :) 

ok so i got that disabling cores was a useless idea :p  as for the other ideas...

-i already am underclocked to 1.6ghz, but i probably could go lower? how far do you think i could/should go?

-use 1x2gb ram vs 2x1gb ram wont work too well for me, as my mobo is dual channel

-i use the radeon to send video to my tv, so pulling that out and using onboard isnt really an option :/ 

-current psu is stock 275watt HE and yea im not sure if i cant get an upgrade for that :p  fyi, specs are here: http://www.dell.com/downloads/global/products/optix/en/... (pg 28)

i will look into a different cooling system though ;)  thanks again
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November 16, 2011 6:35:09 PM

make sure your taking the volts down with the clocks otherwise it wont amke much difference
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November 16, 2011 7:33:45 PM

You can use single channel ram on a dual channel motherboard. It won't hurt anything and you won't notice the difference in speed. It also will only save you like 1W, which equates to $1.37/year savings in NY state with our high electricity costs.

As for a more efficient PSU, you can switch it out and just make a frankenPC, but I don't know how much benefit you'll get. You say yours is the 275HE, which Dell claims is 80% efficient minimum. Upgrading to a 90% efficient PSU will probably save you ~$18/year (with NY prices). So a $80 PSU will take ~4.5 years to pay for itself.

The easiest way to save money is to setup the computer to automatically shut off every night and wake up every morning. I tried that with my server but it had shutdown issues (Gigabyte board with an Atom D525 running Ubuntu 10.04 server). You can even support Wake-on-lan in case you need it earlier than normal.

Also, disable everything you aren't using in BIOS. It won't save much, but might as well disable everything.

Check out - http://www.lesswatts.org/projects/powertop/ - for more ideas, tools, and tips.
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a c 84 à CPUs
November 17, 2011 12:30:44 AM

It's not so much the lower clock speed but the lower Vcore. You'll need to find a lower Vcore if you really want the lowest power draw. I know you are using this to stream stuff to your TV. But the newest GPUs from both AMD and Nvidia have sick idle draw. Many of the cards are between 10-15W at idle.
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a b à CPUs
November 17, 2011 12:31:38 AM

Use integrated if possible tho.
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November 17, 2011 2:52:31 AM

ok so upgrading my psu to a 90% efficiency model isnt really worth the money imo and i dont want to bother changing to ram for such small savings :/ 

ive done some research into vcore vs clock speed, and i think that i can only change the clock speed. my bios does not support changing the vcore, and i only know how to lower the clock speed to 1.6ghz using ubuntu cpufreq applet.

i think this is as far as im probably going to go, so thanks everyone for their advice!! :) 
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a b à CPUs
November 17, 2011 4:42:59 AM

just go into the bios. The optiplex got different power saving features. Allow the OS to power down the UART. Disable the the pci slot if you dont need it. Enable speedstep and enable low power savings mode. All optiplex machines got that features. Also inspect the mobo for bulgy caps as Dell boards got a habit of having weak caps. Thx king_smp for that one as he told me that and found four on the optiplex I got here
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