Re: Going to one HD

mechdan_at_yahoo.com
Date: 08/25/05 

Date: 25 Aug 2005 08:51:37 -0700

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.
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.

>>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.

>For a 90 watt 3.06 GHz Xeon, though, nothing like that
>will do the job.

Wrong. Intel has stock Xeon heatsink/fans with the
traditional layout:

http://www.shop-intel.com/shop/product.asp?pid=SIPS1055&pfid=123&pindex=1&mscssid=3VA07WWPAEXG8JSN5M7UP42R6M7J9QR7

These are not suitable for blade servers because of
the physical constraints of a blade, but they're
perfectly fine for a tower.

>>>But is it cool enough?

>>Yes. A processor is cool enough if it never suffers
>>from the effects of overheating.

>Maybe the O.P.'s processor is cool enough as is, but
>reversing the fan(s) in the power supply could put it
>over the top in heat.

Maybe so, maybe not. You don't know it.

>And if heat is not a problem, why is he changing the
>cooling around in his machine anyway? He must perceive
>it to be a problem.

He also perceived the wattage rating on his PSU to be
a problem--but he was wrong. Many of his other changes
seem to be motivated more by capriciousness and a
desire to tinker than anything else.

I get the impression that he has a vague idea that
"cooler is better", but he doesn't have a firm idea
of WHY cooler is supposed to be better.

>>There is absolutely no reason you NEED to run a processor
>>cooler than you HAVE to.

>For most things electronic, adding 10C to the temperature
>cuts its MTTF in half, so you should never heat things
>more than necessary.

Nonsense. If the MTTF is already far longer than the
expected useful lifetime of the equipment, then who cares?
I wouldn't expect to be using a particular CPU for
more than a decade or so. And if a CPU fails after a
few years, so what? By then replacing it is dirt cheap.

>It just seems dumb to blow hot air on something that
>needs to be cooled.

It happens all the time with PSUs in traditional layout
computers. It's a serious problem, because CPUs generate
more heat than PSUs, and PSUs require lower operating
temperatures than CPUs for reliable operation.

PSU failures are also more problematic than CPU
failures. The symptoms of PSU problems are more
difficult to recognize and diagnose, and they often
cascade into causing mysterious hardware failures in
other components. Worst of all, PSUs have greater
potential for longer useful lifetimes, and don't
depreciate in value quickly the way CPUs do. Replacing
an old PSU costs more than replacing an old CPU.

>>So what? Silent computing almost by definition means
>>breaking the so-called "rules".

>If a processor (actually a computer system) does not
>need to be reliable, why cool it at all? Or why even
>turn it on?

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

>>Why should I, when I can get my current processor
>>to function perfectly fine in my quiet/silent computer?

>Well my Xeons are redlined at 70C processor temperature,
>which implies a lot lower ambient air temperature. When
>the inside of my box gets up to about 52C, the processors
>go up to around 56C or so, and the cpu cooling fans are
>screaming at about 6000 rpm.

So what you're saying is that you have ~14 degrees
to play with and you simply chose to not run it anywhere
near the limits. That's your equipment and your
decision. My equipment is different, and my decision
is different.

Me? My main workstation is a 2.5ghz Northwood. For
various design reasons, the CPU ended up being at the
end of the airflow chain, receiving the warmest air.
The only fan in the system is an 80mm fan running
silently at 5volts. I have a switch to flip it to
12v for reencoding video files, but other than that
I run at 5volts. The machine is perfectly stable at
all times.

When I upgrade to 64bit, I'll be using an even cooler
processor (probably a Venice core A64 unless something
even better comes out). At the same time, it'll be
using even better heatsinks that weren't available
when I put together my Northwood, and the PSU will be
significantly more efficient.

>>You are blinded by dogmatic assumptions. Silent computing
>>is simply not about following established recommended dogma.
>>It's about actually UNDERSTANDING the interplay of heat
>>and temperature and airflow, and creating new solutions
>>using that understanding.

>I am blinded only by Intel's recommended cooling practices
>for the processors I am using.

And yet you dogmatically advise us to blindly obey Intel's
recommendations also.

>Since those thing cost
>something like $750 each (back when I got them; they are
>surely cheaper now), I see no reason not to follow
>Intel's cooling recommendations.

Since that's your equipment and your decision, that's fine
for you. But other people are other people, with other
equipment. I'm sure the OP's processor never cost him
$750, ever, and certainly none of mine ever cost that much.

Isaac Kuo

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