🚀 go-pugleaf

In article <343fd251.5568516@news.demon.co.uk>, "Sam." <sam@greenaum.dem
on.co.ARSE!ARSE!ARSE!uk> writes
>>but if you're interested in super-cooling, the address is:
>
>1.  Chips have a minimum operating temperature. They're only specced
>to about -20 or -50 C.

AND FURTHERMORE...
The life of a silicon semiconductor is exponentially proportional to its
operating temperature. If this never exceeds 100oC then it will have, so
far as anyone has yet been able to determine, a very long life, measured
in decades at least. (This has proved not the case with the old
germanium type devices which are now expiring in droves because they
deteriorate with age, even if you don't use them.)

You don't need super-cooling or even liquid cooling. You just need to
keep the core temperature below 100oC at all times. It should be able to
go to 150oC on a regular basis quite safely & the device can still last
for years.

At the top extremes of the temperature scale its life can be reduced to
hours or even minutes. Of course if this goes on a point will be reached
where there is instant terminal meltdown (it goes "pop").

The faster a chip runs, the more current it passes per unit of time (a
particular characteristic of CMOS technology, which I won't go into
here) & so of course according to ohms law the more heat is generated.
This is why there are now lower voltage options other than 5V (3.3, 2.9,
etc.), these are designed to reduce one side of the equation.

Generally the level of air circulation in the average base unit is
adequate for normal convection cooling. You just need a big enough lump
of metal stuck onto the CPU chip. This lump of metal needs a large
surface area, i.e. lots of fins. The addition of a piggy-back fan is
obviously a good idea, especially in a warm climate.

If you think this is still not quite enough you can do two things:
1. paint the heatsink with cylinder black (from any good motorcycle
accessories outlet); matt black is supposed to radiate heat as
efficiently as it absorbs it;

2. smear a layer of heatsink compound, also known as "Thermapath" or
"silicone grease", on top of the chip before clipping on the heatsink.
This fills in all the microscopic gaps twixt chip & h'sink & has been
claimed to increase conduction by as much as 60 percent. You can get
thermapath from Maplin Electronics, 01702 554171

Oh BTW, if your main fan stops working & you don't do anything about it
your power supply will soon fry itself. Just thought I'd mention it.

-- 
Mike H
Thought for the week:
Is to be "dogmatic" the opposite of pussy-footing around?