And why not go with a cheaper alternative if it works?
It's cheaper for Dell, not necessarily for us. They would likely hit
the same price-points either way.
Sure, the Dell duct cooler may run hotter ... but Dell's main interest is
RMA's, and if their coolers didn't keep systems stable they would do
something different.
I suggest a reread of the OP, which <> stable.
Someday when boxes are static, sealed systems like a VCR, it could be
a good standard to follow, but PCs are user-configurable devices, even
if it does void the warranty. A chassis that's not very forgiving of
airflow changes can't accomodate user upgrades and/or may not last as
long. Why would Dell care about that... after all, it'll last till
the warranty is up so long as nothing is changed (which voids the
warranty), they assume.
The truth is, duct cooling systems ARE better ... they allow Dell to get
away with what would seem crazy in terms of the number of fans and
individual fan speeds.
Fans have been around a long time, it's not crazy or hard in any way
to put an appropriate amount of cooling in a system... no more, no
less. Better is relative... it's better for Dell, but not
necessarily for their customers. Dell as well as anyone else has the
resources to build quiet PCs with fans on the heatsink. What they did
instead IS an acceptable method of cooling, but still inferior when it
comes to noise... Yes, it's LOUDER. A ducted fan requires higher RPM
to move the same amount of air, and there is more turbulent noise
escaping the chassis. A lower-RPM rear fan with no duct can be
quieter while moving same amount of air though the system, while the
heatsink fan can have even less noise escaping the chassis than the
rear fan, and keep the CPU cooler than Dell's method.
Imagine a duct system with a whisper quiet 120mm fan pulling as much air as
3 or 4 loud 60mm fans using a well made oversized copper passive heatsink.
Imagine same 120mm fan without the duct, so it has a better airflow to
noise ratio.
120mm fans are great for moving a lot of air quietly, but it can't be
forgotten that axial fans are low-pressure air-movers, having a large
fan ducted down to create vacuume to pull air though a heatsink isn't
optimal airflow, it would be better to use a diagonal fan (which BTW
is not a mounting position but airflow characteristic), but even then
to maintain high enough airflow through the duct to have temps
parallel to active 'sinks, the fan would have to spin fast enough (or
an alternate type fan producing more noise at same RPM would be
needed) that it's not what most people would consider quiet->silent.
It would blow away any active cooler you can name.
It won't, because fans that create a lot of vacuume are noisey.
Without more vacuume than a traditional fan can provide at low noise
levels, there will always be less airflow though the heatsink than a
fan [of same or lesser (operating) noise while] atop a 'sink.
Users everywhere with these Dell sytems have higher CPU temps than
people using _good_ active coolers. The idealistic notions of the
ducted cooling system are contradicted by fact. The fact is that a
fan mounted on a heatsink can be quiet and still move more air through
the 'sink than the duct will, which results in lower temp. The
difference is great enough that air recirculated though the 'sink
doesn't reduce the effectiveness to the lower level of a ducted
cooling system. Removing the duct also allows the rear fan to move
more air. Greater airflow to noise ratio results, in addition to a
lower CPU temp.
The downside to active heatsink cooling is not performance, it's cost,
and possibly strain on the socket (or other mounting with a P4) during
transportation. Dell can buy 120mm fans and ducts in bulk for low
prices, unlike the situation an end-user will see, where a simple duct
is generic, not custom-designed for the system, and still costs WAY
too much for being a relatively simple piece of plastic. A relatively
elaborate, effectively designed duct might help, but would then might
be more expensive, less immune to dust buildup, and still it won't
change the anemic vacuume of the fan.
all that hot air outside of the case ... which would keep the internal
ambient temperatures down.
An oversimplified theory which goes against the evidence that our OP
and other Dell owners have hotter running CPUs. It's a good idea to
get the hot air out without it recirculating, but doing without the
CPU 'sink fan is not helping to accomplish that. If Dell had chosen
to they couldn've put a silent fan on the 'sink and still used a
duct... I'm not aways against ducts, but there are usually unnecessary
and often not a good substitute for active cooling.
Just because Dell doesn't implement it to the best of it's potential doesn't
mean that it's inferior. In fact, it's what allows Dell to achieve stable
performance with such (on it's face) inadequate cooling.
It's inferior from a cooling standpoint, almost equal from a noise
standpoint. A well-designed duct might be used, but we can't be so
sure Dell hasn't weighed all the alternatives and that their duct
isn't the best implementation from their perspective. It would have
to be the OEM's perspective at issue, since end users or smaller
builders have more variable cases and motherboards to consider (or to
put it another way, higher cost due to low volume, per each duct
design), so a custom duct could only be made at great expense or
hand-made, taking a fair amount of time (and to some time is money).
A duct in itself isn't necessarily a bad addition to a system, but it
does have different benefits than an active cooler. Lower temps,
lower noise, aren't two of the benefits unique to a duct-cooling
strategy... it's just that so many crap coolers with junk high-RPM
fans are out there, that duct-cooling is good in comparision to the
lowest-cost alternatives.
Dave
