[rescue] This Just In: HP to buy Compaq

[Greg A. Woods]

[ On Monday, September 17, 2001 at 09:48:19 (-0500), BSD Bob the old greybeard BSD freak wrote: ]
> Subject: Re: [rescue] This Just In: HP to buy Compaq
>
> It is a function of both air velocity and dissipative cooling capacity.
> In confined spaces, you need cooling air velocity.  In open spaces you
> need sufficient area to dissipate the heat away from the device.

Ah, Bob, the amount of radiated heat is going to be pretty much exactly
the same in all cases, and in open spaces you get "dissipation" by way
of the convection currents that are created when the heated air rises
out of the heatsink and thus draws more cool air into the heatsink.....

I.e. you still need cooling air velocity, but in open spaces the
naturally generated convection currents alone are what's providing that
air velocity.

> I gotta admit, though, my alphas tend to run hotter than I would have
> designed them to run, especially the little power regulator off to the
> side of the cpu.  That thing runs normally hot enough to cook an egg.
> The alpha manual says not to run the thing (3000/300) with the lid off
> or the cpu will burn up.

I don't know about modern process high-density ICs, but back when I went
to school the average power IC could stand a junction temperature of up
to 200C before self-destructing.  That's certainly hot enough to cook
any egg I know!  ;-) Even taking the junction-to-sink thermal resistance
into account that's probably still a good 120-150C, and that'll still
cook my eggs just fine (though a bit slower....  :-)

-- 
							Greg A. Woods

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