[mythtvnz] New motherboard

[Steve Hodge]

On Tue, Jun 14, 2011 at 18:13, Stephen Worthington <stephen_agent at jsw.gen.nz
> wrote:

> An Athlon 64 3200 should be fine for recording as many channels as you
> need, but if you want to run transcoding on everything it will be a
> problem.  It should be able to do mythcommflag on everything for you,
> only on one program at a time, and it will be running the CPU hot for
> a fair part of each day.  A more modern CPU will probably cost less on
> your electricity bill to run.
>

Since I just upgraded my desktop from a Athlon 64 3500 to a Core i5 2400 I
thought I'd run the numbers to see what the saving is really like.

Depending on exactly which Athlon 64 3200 we're talking about, the TDP is
between 59 and 89W. Let's use the 89W. My Core i5 has a TDP of 95W.
The benchmarking I've done seems to indicate that the Core i5 is about 10
times faster than the Athlon 64. So, using TDP as an indicator of power
used, a job which takes 1 hour on my Core i5 would take 10 hours on the
Athlon. The Core i5 would use 95Wh, the Athlon would use 890Wh. So about 80W
more per hour of use. 1kWh costs about 15c and the Core i5 cost me $250.
So...
$250 / .15 = 1666 kWh = 1666000 Wh of electricity.
1666000 Wh of electricity is wasted by the Athlon in 20833 hours at 80W per
hour.
So best case scenario, upgrading to a Core i5 breaks even when you've done
the amount of processing that would have taken 2.4 years on the Athlon. In
reality I don't think transcoding will be 10 times faster and the Athlon's
power usage may be significantly lower than 89W.

It seems to me that the power savings are a poor justification for
upgrading. Reducing CPU heat generation might make it worth while though.

The big surprise for me in upgrading is how much quieter the fans on the CPU
and graphics card are (Sapphire Radeon HD 6850). Despite having those two
fans, the power supply fan, and 3 case fans the drives are the noisiest
components.

Cheers,
Steve
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