[rescue] Prices... Amazing

Nathan Raymond nate at portents.com
Mon May 2 14:04:19 CDT 2005

On Mon, 2 May 2005, Rox wrote:

> On 2 May 2005 at 14:22, Nathan Raymond wrote:
>> No, that's not accurate at all to assume they'll put out the same heat
>> based on power draw.
> Really? In what form does the energy leave the system, if not as heat?

I was operating under the (perhaps wrong, someone correct me here if I am 
wrong) assumption that capacitive loss doesn't produce heat.  Since I 
could be (very) mistaken on that point, let's discard everything I said 
about CPUs.  Someone with a stronger EE background want to chime in here?

In any given computer system electrical power gets used to move fans, 
drive spindles, optical drive motors, current on ports that go out of a 
system (serial, USB, video, etc.), the list goes on and on, and that 
doesn't necessarily produce any additional heat in a computer's case, or 
certainly not the type of directly correlative heat like leakage current 
where you can take a watt value and say that this much heat is going to 
come out as a byproduct.

And ignoring that, like I said, different power supplies are going to have 
different efficiencies, and you won't know what the efficiency of a given 
power supply is for a given load (i.e. how much power is actually being 
consumed at the outlet and how much heat is atually being produced) until 
you measure it, making anything other than real world measurements for a 
specific configuration a good guess.

- Nate

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