[luau] Underclocking / Aluminum cases

[Jim Roby]

Interesting aside,regarding fan flow direction.When IBM engineers
put together the first XT they admitted that the best logical cooling
would be for the PS to suck air in,not out,and concidered doing this
with a paper element filter to trap dust...then they realized the user
would never change the filter and all cooling would stop,thus they opted
for what they concidered the second best.
 On Wed, 3 Jul 2002, MonMotha wrote:

> Yuser wrote:
> >>Robert Green wrote:
> >>
> >>
> >>>Your idea of just leaving the cover off is less efficient than a
> >>>well-designed case with good air flow via a case fan, unless you're
> >>>going to use a room fan to blow into the open case (or other method
> >>>to increase the air flow across the components).
> >>>
> >>
> > 
> > I agree with this in theory but I have not seen it in real life.  I have
> > two computers with MB/CPU temperature monitors.  Both temperatures run
> > roughly 10F cooler on both computers with the case off.  Maybe these are
> > not well designed cases but I have not seen generic ATX or AT designs that
> > were really any different elsewhere.  Proprietary cases on mass produced
> > PC's do seem to have some flow characteristics designed into them but they
> > usually include some type of ducting to get it done.
> > 
> 
> 
> I guess you've never used a Dell Dimension XPS Dxxx series tower system. 
>   The processor has a big heatsink but no fan on it.  Directly behind 
> the processor is the case fan.  Take the case off an run the CPU at 100% 
> for long, proc overheats and halts.  With the case on, run at 100% CPU 
> for days, the heatsink is barely warm to touch.
> 
> I've actually built white boxes with similar, though not so drastic, 
> thermal characteristics.  When I build systems, I usually consider 
> airflow from the start, even down to selecting different brands of video 
> cards due to how far back they extend!  I route cables behind things, 
> twist tie cables next to bracing, etc. all to improve airflow from front 
> to back (I've even built a wacky system where I flipped the PSU fan and 
> had air flowing from back to front).  Most of my systems, when I'm done, 
>   have case temps within 0-3C of room temp, and CPU temps within 0-10C 
> of case temp, but I've had systems where, due to good airflow, the CPU 
> runs hotter with the case off (even though sometimes ambient system temp 
> is lower) than with the case on.  Good airflow allows for faster 
> evacuation of the hot air produced by the CPU fan circulating air over 
> the heatsink, thereby lowering the ambient temperature NEAR THE CPU, 
> creating a greater delta T between the heatsink and air, allowing for 
> faster heat transfer from the CPU heatsink to the air.
> 
> --MonMotha
> 
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