Re: 24" iMacs run hot!

My whole point was that the temperature of the exiting air is
extremely indicative of the cooling design. That by just holding your
hand in front of the exhaust you can instantly tell things - as long
as the computer is not doing some resource demanding tasks

But you agreed with my scenario of the 2 computers with different sized
heatsinks inside expelling the same amount of heat ... so holding your
hand in front of the exhaust doesn't help you.

So to maintain the same temperature the airflow has to be regulated in
one of them to match the temperature in the other one.
The problem is that is not the way you regulate temperature in a good
design. You run the fan at the highest inaudible speed. Then you use
a heat sink that dissipates enough heat to keep things cool. You're
depending on airflow for cooling. Airflow (due to noise restraints)
is very limited. You need to depend on heat sink design instead.

All I know is that if you used a massive heat sink it wouldn't even
get warm. The small amount of air movement would pull any rise in
temperature away with the result that exiting air would be near the
ambient temperature. Maybe some of you are making this a lot more
complicated than it need be.
1 - Cool with external air.
2 - Exhaust heated air immediately.
The only way to do this that I can tell is for motherboards to be
designed for each heat generator (CPU, Video card, chipset, ram) to be
mounted on the corner. Otherwise its hard to exhaust the air without
that heated air affecting something else. As components get hotter
and hotter, this will become more and more critical. Designers have
been able to get away with cooling with warm air for a long time. But
won't work for much longer. The Mac Pro is a step in that direction.
A very compromised design, mind you, but its a step. Cooling the RAM
heat sinks with hot CPU heated air doesn't seem very logical.

Here's a product designed to lower the temps of the Mac Pro's ram:
http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&;
Product_ID=160
But the silly thing is they are not addressing the source of the air.
Its coming right from the CPU heat sinks, the largest heat generator
in the computer. Too bad they couldn't duct the CPU heat out the side
of the case, then pull in the RAM cooling air from the bottom ducting
it out the back like it presently is. If you're going to go to all
the trouble to put huge heat sinks on the ECC FD-Dimms, doesn't it
make sense not to blow hot air on them?

Maybe in the next version of the Mac Pro they will have positive air
cooling on the hard drives (all 4 instead of sort of cooling the
middle 2 only) instead of cramming them upside down so the heat is
trapped (hard drives radiate far more heat from the bottom than the
top). And have some of them hooked up with eSata so they are hot
swappable and accessible from the front. That would be great for
people working with large HD video files. To have to open the case to
change a hard drive (not to mention having to shut the system down, is
just wrong. I'm sure eSata is on its way. 3 gb/sec plus hot
swappability is great for everybody. Sure beats firewire. Too bad
Apple has such a close relationship with firewire. It might take
longer than it should.
.

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