[mythtv-users] MythTV backend running on NVIDIA Ka-el, 35W replaced by

[Raymond Wagner]

On 3/8/2011 20:28, mythtv wrote:
> The primary reason I want to reduce my power footprint right now is that
> my combined BE/FE sits below my TV and the fan is noticeably loud.  My
> current HTPC case is sadly limited in system fan options and my PSU fan
> seems to ramp to 100% (loud) at 55C.

Can you just move this machine to another room?  I've got my combo fe/be 
in the basement under one of my TVs, and I just cut a hole in the floor 
in the corner behind the TV to snake audio, video, and USB up through.

> Intel Core 2 E6600
>
> Viewing content vs idle doesn't make any noticeable difference in power.
> I'm a little more surprised that recording 4 shows simultaneously only adds
> a few watts on top of the 85W baseline.

That E6600 should be dropping multiplier, and dropping the voltage to 
match.  Unless you're using VDPAU for all your decoding and idling all 
the time anyway, there should be a noticeable difference between 
playback and idle.  Check /proc/cpuinfo when your system is idle, and 
see what it thinks your clock speed is.  It should be something well 
below the stock 2.4GHz.

> After my RAID array had a failure I replaced a 3.5" drive with a 2.5" one
> and noticed about 5W less power.  So I moved everything except my 1.5TB
> drive to 2.5" disks as time and budget allowed.

A 2.5" hard drive may use less than half the power of a 3.5", however 
three 1TB 2.5" drives will consume more than one 3TB 3.5" drive.  Make 
sure you have your system set up to allow idle spindown.  An idling 3.5" 
hard drive will consume 4-6W each, but ones that are parked and spun 
down will be well under 1W.

> I'm seriously thinking about experimenting with the PicoPSU 130W as a way to further improve my power efficiency without a large expense.

The PicoPSU itself is going to be 96-98% efficient, but you still need 
to get DC in the first place.  Most external switched mode supplies are 
going to be around 70% efficient, and you can get some real crummy ones 
closer to 60%.  The linear rectifiers in wall warts are even worse than 
that.  Unless you're looking to do something fancy, like run DC power 
throughout your home, look up a computer directly to a UPS, or power it 
straight off a solar cell, the only thing a PicoPSU is going to allow 
you to do is move the heat and bulk of a normal ATX PSU outside the case.