Skybuck said:
Let me know when you find the "air displacement" or "air flow" of it's
fan...
I've giving up on finding it especially with todays BLOATED WEBSITES.
You should try it yourself with a 450 mhz and 256 MB ram.
Hilarious to see all that BLOAT CRAP.
Fortunately some websites are better then others.
Bye,
Skybuck.
The math is pretty simple.
Room air temperature 25C.
Well cooled PC (using that equation with the 3.16 factor in it), will have
an internal temperature of 32-35C or so. Since you as the designer know the
total PC power dissipation and the size of the fan used on the case to cool
the air inside the PC, you control that.
So let's say the internal air is 35C. That might be sufficient to keep
the hard drive happy. The processor can take the heat, while an
overheating hard drive is a bad thing. So a steady movement of cool
air in the case, with perhaps the intake air hitting the hard drive, is the
best thing.
The provided retail heatsink with an AMD or Intel processor, has a theta_R
(thermal resistance) of around 0.33 degrees C per Watt. If the processor
is 89 W, 0.33 C/W * 89 gives a delta_T of 29.4C. Add that to the 35C
internal air temperature, gives 64.4C as the processor (casing) temperature.
The processor has provisions for throttling, so if an over-temperature is
detected, the processor either reduces compute rate or the computer is
totally shut off. If the retail cooler isn't sufficient, for the room
temperature range in your room, then you find an enthusiast cooler. But
many modern processors, don't really need cooling modification.
And that means, you can safely build a PC with the retail provided cooler,
and if the measured temperatures aren't suitable, you can put an enthusiast
cooler in it. Enthusiast coolers have a theta_R of 0.15 to 0.22C/W and
use things like heat pipes and large fin assemblies to achieve that
level of thermal resistance.
Not too many manufacturers of heatsinks, rate their products in theta_R.
Zalman has, for some of their older products, and based on that,
we have some general ideas how good they are.
A tool like Throttlewatch or RMClock with it's graphs, can show you
whether the processor is throttling while running a stress test like
Prime95. If you see throttling, then a better cooler may be required,
or an adjustment of the case cooling is needed. Air must be flowing
past the processor socket, to carry away the heat coming off the
CPU cooler fins. If you have the world's best CPU cooler, and the
worlds worst case cooling design, then it could run too hot as a
result. You have two adjustments you can make, either increase
case cooling airflow, to lower the internal case temperature,
or use a larger cooler with heat pipes, to reduce the delta_T between
processor case temperature and case internal air temperature.
AMD and Intel rely on System Builders, to apply the above kinds of
math, to build good systems. IT is not the job of AMD and Intel,
to make your computer for you. But with a little work, you can
manage that for yourself. Many home builders have learned enough
about cooling, to get their PC to work.
Paul
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