[mythtv-users] Heat issues with USB ATSC tuners?

Joseph Fry joe at thefrys.com
Sat Sep 1 05:49:40 UTC 2012

> Even 500ma at 5v (2.5w) is significant to me - I'm trying to build the
>>> lowest power machine possible, and 7.5w for three tuners is almost as
>>> much as the whole rest of the system...
>> This all really seems like far too much ado about nothing. Unless you're
>> talking about off-the-grid operation, electricity is cheap. For a piece of
>> hardware running all day, every day, it typically comes out to around
>> $1/W/yr.
> (based on the US EPA's published national average)
>    Is a couple bucks really worth all the heartache you're putting into
>> planning such a low power device?
> So going from a (poorly-designed) Core 2 Duo or Core i system that
> averages an 80W draw and running it 24/7 for a year costs you ~$80.  When
> you drop that to a (typical) Core 2 Duo or Core i system that averages a
> 40W draw and run it for 24/7 for a year, you've saved $40/yr.  So, just by
> choosing to not buy an inappropriate system, you can ensure your MythTV box
> costs you at most about $40/yr in electricity.
> So, say that your system actually takes 7.5W and you get a magical 0W
> tuner.  That means you've saved $32.50/yr over a typical PC (a typical PC
> with lots of headroom for when you need it, BTW) by using your low-power
> solution.
> Now, if instead, you take that 40W PC with lots of headroom and configure
> it to shut itself down when not in use and to wake up when required for
> recording or playback, it may draw about 40W when in use and 0W when not.
>  If you assume you'll average about 4hrs/day, that will cost you
> $6.67/yr--saving you $33.33/yr (more than you save by going to this 7.5W
> system).
> So, you may think, "Well, I could have the best of both worlds--take my
> 7.5W system and shut it down when not in use!"  That's actually true, and a
> good idea, but notice that if you do, you're going from $7.50/yr to
> $1.88/yr, which means you're only saving $5.62/yr for this change.  Still
> worthwhile because there's no real loss for turning off the system when not
> in use, but there's not a lot left to optimize in the setup/not a lot of
> savings to be had, here.
> In other words, a) the best way to save power is to shut off the system
> when not in use and b) there's a point of diminishing returns on reducing
> power, and you likely have far bigger wastes of power around your house you
> could concentrate on fixing.

Actually the best way to save power is not to have the system in the first
place.  These discussions crack me up when I actually take a minute to
think about them.

Honestly, if $30 worth of electricity over the course of a year is cutting
into your food budget... don't use mythtv at all... it's a luxury and a
hobby that can be quite expensive.  Now, if part of the enjoyment of the
hobby is trying to build a system with the lowest power requirements
possible... mostly because of the challenge of it... thats a different

Of course we would all love a powerful mythtv system that ran on perpetual
energy... but until then I will take my full powered flexible and long
lived systems over a low powered, limited, and likely soon to be obsolete
system any day; at least I have some hope of using new features.  For
example 0.26 brings HLS... impractical on a low powered backend.  Who knows
what 0.27 and 0.28 will bring.
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