Re: [gentoo-user] gnome login panel how to disable restart and shutdown buttons

[Mark Knecht]

On Tue, Apr 27, 2010 at 8:50 AM, Paul Hartman
<paul.hartman+gentoo@×××××.com> wrote:
> On Tue, Apr 27, 2010 at 10:21 AM, Mark Knecht <markknecht@×××××.com> wrote:
>> Computers are a big portion of the bill around here and learning how
>> to reduce power is high on my priorities for the next few months. I'm
>> not sure how to handle a multi-use box like this. It's an 8-thread i7
>> processor. I was wondering about powering off certain core when the
>> machine isn't doing much. Does Intel hardware do that? I need to
>> determine how much power is in the processor, the chipset, memory, the
>> disk drives. The machine is 3-drive RAID1 using data center drives.
>> The WD Green drives just didn't work for RAID. I'm sure 3 drives is
>> adding to my power consumption, but maybe they can be spun down more
>> often. Myth recordings are currently stored on an external USB drive,
>> so that's more power.
>
> Supposedly enabled and idle cores use even less power than disabled
> cores because of the way the i7 handles C6 state. Intel claims power
> usage in this state is approximately zero (not even any leakage).
>
> Enable C1E and EIST in your BIOS (they are powersaving options),
> enable CPU frequency scaling in your Kernel and use ondemand governor
> (As you would on a laptop). Disable unused network interfaces or SATA
> controllers etc. in BIOS.
>
> NVidia cards using the proprietary drivers have powersaving and
> underclocking options (enable the option "Coolbits" in your xorg.conf
> and then use nvidia-settings to see these extra options)
>
> I don't know if PSUs consume more power than necessary. For example if
> you have a 650W power supply but could have gotten by with 380W, could
> you save energy by using the smaller one? I'm not an electrical
> engineer. :)
>
> My new system has Samsung drives that seem to have a pretty aggressive
> spindown time (at least compared to my old ones, which never
> spundown). I was concerned about this in my RAID5 but what I have
> really learned was how often my disks are idle. The spindown isn't so
> aggressive that it happens while I'm actively using the system.
>
> I am curious if enabling laptop-mode would have any positive effect on
> a desktop that has these CPU & HDD power saving features? Or perhaps
> disabling swap entirely and putting temp directories in /dev/shm.
> Basically the same kind of techniques people having been using on
> laptops for years to reduce disk activity and power consumption. It's
> an experiment for a rainy day :)
>
>

Really great info and ideas Paul. Thanks.

I've been playing a lot with power measurements here in my home
office. I've got three machines each with their own UPS, two internet
connections, 5 monitors, a couple of switches. It all adds up. It's
been interesting to look at where the power goes.

Keep in mind that my incremental power costs right now are $0.42/KWH.
For monthly costs I use 24*365/12 = 730 hours/month.

1) Everything shut off except the power strip plugged into the wall. 5
Watts. Just this power strip plugged into the wall driving 3 UPS's
that are turned off costs me $1.53/month. For a power strip? (It has a
green and red light!)

2) With all the computers and monitors turned off but the UPS's
powered on I used about 25 Watts, so that's about $7.50/month.

3) At idle the laptop uses 75 Watts with no external monitors, 125
Watts with a 23" external monitor. IF I have it on 16 hours/ day
that's about 2KWH per day or 61KWH/month for a $25 bill.

4) My new i5-661 desktop driving two external monitors actually uses
the same 125 Watts as the laptop so that's another $25/month.

5) My new number cruncher based on the i7-980x with 12GB DRAM, 5 hard
drives and two external monitors is about double that at 260 Watts.
Simply for power consumption reasons I cannot afford to run it 16
hours per day, and I don't need it that much anyway, so I only turn it
on when I have a few days worth of number crunching to do. It's
probably costing me $10-$20/month since it's on less than 20% of the
time.

All in all it turns out I'm spending close to $75/month ($1K/year)
just in my office!

Getting power down is important to me!

- Mark