🚀 go-pugleaf

In article <80ttgr$1aq2@gamma.dmz-eu.st.com>, Dave Smith
<dsmith@bristol.nospam.st.com> writes

>In article <f6ps08.c43.ln@stravinsky>, anahata@freereed.demon.co.uk wrote:
>|> Overheating is a separate problem.  It can be a consequence of overclocking,
>|> and overheating can cause errors, but that's not the only reason why an
>|> overclocked device goes wrong. If the logic can't respond fast enough to
>|> have the right data at the output when the next clock pulse arrives, there
>|> will be errors, simply because the internal logic can't move fast enough (at
>|> any temperature).
>
>Rubbish (sort of).  Device Speed is always a function of temperature, i.e. the
>hotter it is, the slower it runs.  

Garbage. You have your cause and effect mixed up.
Actually IIRC conventional silicon semiconductors run slightly FASTER
when hot because of a *small* increase in electron/hole speed.

>Extra cooling in overclocked machines has two
>functions:
> o Stop the device from exceeding a safe temperature limit, beyond which the 
>chip
>   can be physically damaged

Correct.

> o Keep the device as cool as possible, to maximise the speed at which it can 
>run
>   The colder a device is, the faster it will run.

Crap.

>A device which will only run at it's rated speed with normal cooling will be 
>able 
>to run faster if you can keep it cooler.  

Correct. As has been said above the faster it runs (assuming the chip
fabrication actually permits this, ie switching speeds and internal
delays permitting) the more heat it GENERATES so to dissipate the heat a
colder chip SURFACE temperature is required to prevent meltdown/devices-
going-out-of-spec. Please note and understand heat diffusion and
temperature between ambient and junction. If you don't understand this
then you don't have a clue what's going on and would be well advised to
shut up.

>This is the reason why the Cool Athlon 
>machines can run at such ridiculously high clock speeds, because they have a
>built-in refrigeration unit to keep the CPU very cold.

No, it's to maintain the chip junctions within their thermal limit and
STILL dissipate the greater heat produced by the elevated switching
speed.

-- 
Oz