[mythtv-users] Architecture Idea - Raspberry Pi, VM, XBMC

Christopher Kerr mythtv at theseekerr.com
Tue Jan 15 04:52:29 UTC 2013


On Sun, Jan 6, 2013 at 4:03 AM, Roger Heflin <rogerheflin at gmail.com> wrote:

> On Sat, Jan 5, 2013 at 10:22 AM, Raymond Wagner <raymond at wagnerrp.com>
> wrote:
> > On 1/5/2013 09:37, Roger Heflin wrote:
> >>
> >> The baseline Atom board with a good power supply runs
> >> about 30-40W at idle
> >
> >
> > Thats awful! My 3.1GHz Ivy Bridge with a middling power supply only runs
> > about 25W idle.
>
>
> It is a 3 year old machine measured at the outlet plug.
>
> What kind of meter are you using to measure that?
>
> My ivy bridge laptop runs 17W at idle with the screen off, and that is with
> a low power laptop cpu vs a high power desktop cpu and for the most part
> most
> of the desktop motherboards don't do that well on power savings at the
> mb level, where
> the laptop chips are setup for power savings.


Way Off Topic:
17W at idle is incredibly high for a laptop.

Without knowing the specs of your laptop, my experience would lead me to
expect an Ivy Bridge laptop to idle at ~5W with the screen off and the CPU
at idle.

My 4+ year old Core 2 Duo can do 9 Watts with the screen on its lowest
brightness setting (tested using a lab-grade Fluke), dropping to around
6.5W without the screen. Ivy Bridge can power gate whole cores and the GPU,
so I would expect it to do substantially better.

I can imagine that under Linux there may be problems with some of the
throttling features, and if your laptop includes a discrete GPU with a
switching technology like Optimus it may be not operating correctly,
leaving the dGPU powered constantly, but that reflects more on the OS than
the hardware.

I remember seeing something (Phoronix maybe?) where a Macbook Pro tested
under Ubuntu used about twice as much power as the same system running OS X
- I wonder if something similar is at work here?

- Chris
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