On Tue, Apr 27, 2010 at 10:21 AM, Mark Knecht <markkne...@gmail.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 :)
