Re: Going to one HD

From: Peter T. Breuer (ptb_at_oboe.it.uc3m.es)
Date: 08/25/05 

Date: Thu, 25 Aug 2005 18:14:51 +0200

mechdan@yahoo.com wrote:

> Jean-David Beyer wrote:
> >mechdan@yahoo.com wrote:
> >>Jean-David Beyer wrote:

> >>>Then why does Intel suggest blowing cool air horizontally
> >>>over the heat sinks?

> >>Huh? That only makes sense if the heat sink is of a
> >>"tower" heat pipe design.

> >Not at all. If you blow down instead of parallel to
> >the heat sink fins, you need a larger heat sink, and
> >more air flow from the fan, to get the same amount
> >of cooling.

> Put bluntly, you don't know what you're talking about.

He knows as much physics as you or me, I daresay. If you blow DOWN then
each (half) volume of air passes over at max HALF the available surface
as it spreads out both left and right on hitting the center of the sink.
In actuality, some will be bounced off the air already rising and
bouncing back up, so it won't contact the surface at all.

If you blow SIDEWAYS, however (or even better, from below - but that's
impossible ;-), then each volume of air travels across the whole plate,
achieving maximum heat transfer through maximum contact .

> There are reasons why the overwhelming majority of
> heatsink fans are designed with fans blowing downward
> onto the heatsink fins. For one thing, they actually
> do indeed work, amazingly enough.

But they don't - not very well, anyway. It would indeed be much better
if there were a tall finned cooling tower and the air were blown
sideways through it.

> >>Have you ever seen a stock CPU heatsink/fan? Why
> >>do you suppose they all have fans blowing into the
> >>heatsink?

> >Of course I have seen the ones you mean. For small
> >slower processors, they provide "enough" cooling and
> >are simpler, mechanically, to install. For something
> >like a 166 MHz Pentium a tiny little fan blowing on
> >a trivial heat sink will do the job.

> The stock heatsink on even the fastest hottest Intel
> P4 Prescott core is of the same traditional heatsink/fan
> design as always. The fan blows downward onto the
> heatsink fins. The Prescotts generate more waste heat
> than just about any processer ever designed.

Heatsink and fan designs are not generally adequate, they just generally
ARE. It's a lottery.

> You continue to repeat this straw man. Quiet PC
> enthusiasts don't skimp on reliability.

My P3 1GHz runs without fan, underclocked. My P100s run without a
heatsink.

Peter

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