[mythtv-users] Quick opinions

Raymond Wagner raymond at wagnerrp.com
Sat May 30 17:35:40 UTC 2009


Andrew Burgess wrote:
> If it ran twice as fast at twice the power it would only run half as
> long so use the same energy (energy = power * time). But it runs more
> than twice as fast so would run less than half as long so less energy.
>   
You don't seem to understand what he is saying.  It's 2.7GHz chip versus 
a 2.6GHz chip, or roughly 4% faster.  Now the 7750 is a newer core 
(based off the Phenom) so it's it does more per clock cycle and has an 
L3 cache, but benchmarks put it somewhere between 5% and 20% faster than 
the 5050e depending on the application.

Now on the power side, the 7750 uses about 40W more under load, than the 
5050e, which outweighs the gain in speed you get with the 7750, even 
when you take into account the consumption of the rest of the system.  
Lets look at the two usage scenarios you have for mythtv.  First, you 
run the machine all the time.  The 20W lower idle is really going to 
matter on a machine that will be idling probably 20 hours a day.  
Alternatively you have the machine running when you use it, and then 
it's put into standby.  The 5050e is still going to use less power under 
load, so again, will be more efficient.


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