🚀 go-pugleaf

Dave Smith wrote:

> 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).
> 
> Device Speed is always a function of temperature, i.e. the
> hotter it is, the slower it runs.  
...

As Oz says, this is nonsense. I won't duplicate his, correct, 
arguments, but will raise one point which isn't clear from his 
debunking: in a PC, or anything else where timing is determined by a
clocking oscillator, speed is _entirely_ determined by the oscillator
clock speed. If the chips are up to it, it'll work, else not. (The 
"clock speed" heere is nothing to do with the time-of-day clock.) 
"Better" chips, a different temperature, etc. etc. will make ZERO 
difference to running speed at a given clock speed. If the chips 
aren't up to the speed (but otherwise OK), reducing the master clock
speed (i.e., reducing the frequency) will make them work, but at a 
slower speed due to the reduced clock speed. If the chips are having
trouble due to overheating at a given clock speed, cooling may bring
them back to a working state; but no degree of cooling will help if 
the chip simply isn't up to it.

There is an extra issue with memory: to simplify, if memory is too 
slow to run flat out it can often be made to work without slowing 
down the system clock by adding "wait states", which slows down the 
system to some extent.

One related point: there is a relationship which depends upon the 
type of circuit used, between speed and power consumption. heat 
generated depends strictly upon power consumption. Some logic chips 
(TTL) have power consumption independent of operational speed. 
Others, including, I believe, most modern microprocessors, consume 
power more or less proportionally to clock speed. This is why faster 
clock speeds need more cooling: the faster clock causes more power to 
be used.

All else being equal, increasing the voltage of the power supply can 
squeeze a little more speed out of chips (i.e., make them keep 
working at a higher clock speed). It also increases power consumption 
and heat generation, and an excessive voltage itself can do damage 
even without overheating.

The effects of _moderate_ overheating are likely not to be permanent 
(otherwise failure of the processor fan would destroy the processor). 
Overvoltage may or may not produce permanent damage, but it's best 
not to risk it unless using a voltage known to be safe for a 
particular chip.

Best wishes,
-- 
Michael Salem