It's something of a point of pride,
I should think.
The CNPS3100G
is the fancy-pants kit-and-caboodle version of their "Flower HeatSink" (FHS),
with more fins than the basic version and and all modern conveniences. You
get mounting hardware and a syringe of thermal grease included in the box.
Zalman sell
this kit directly on their Korean site for 51000 Won, or $USD48,
plus shipping. Shipping for European, North American or Australian customers
is, according to this
page, another $USD33. So you might like to peruse Zalman's list
of dealers to see if there's a stockist
closer to you. Zalman's US branch has an on-line
store too; they have the CNPS3100G for
$USD52.95.
Even if you buy it from a local
dealer, this isn't a cheap cooling solution. But the descriptive blurbs
on Zalman's site
describe the FHS as the "World's highest performance heatsink", and it's
undeniably unique. Unlike every other air cooler in this comparison, the
3000-series Zalman setups don't have a fan mounted on the heat sink.
There's a reason for that. The heat
sink is an extraordinary assembly of 56 copper leaves (gold plated in this
"G" model!), all clamped together at their base but are springily free to
move at the top.
That stripe in the middle of the
cooler's underside is the clamped-together fin bases.
The fins are not at all floppy -
they twang like a medium-thickness feeler gauge, and you can perfectly safely
sit the FHS upside down on a table without its weight bending any fins.
But there's still no way to attach a fan directly.
Instead, you get this 80mm fan on
a bracket that lets you screw it to the top of your expansion card slots,
and position it so that it blows down onto the heat sink.
You don't have to use the provided
fan, of course. The FHS is well suited to fans of various sizes, because
the fins are themselves ventilated...
...like this, to aid air flow. A
60mm fan close to the sink will thus still be able to cool the outer fins.
The total fin spread means that a bigger fan shouldn't be sending too much
of its air flow past the cooler, either.
Apart from the remarkable design
- and it really is remarkable, in a world full of simple metal porcupines
with a fan on top - Zalman also make much of the low noise capabilities
of their products. The "CNPS" at the beginning of their coolers' names stands
for Computer Noise Prevention System.
The simplest way to make a heat-sink-and-fan
CPU cooler quiet is just to slow the fan down by reducing its supply voltage.
That's all there is to it. If you halve the fan voltage, you'll reduce its
air-moving power to roughly a quarter of what it was, because DC power equals
volts times amps, and the fan motor's amp draw falls roughly in proportion
to the supply voltage. At quarter power, pretty much any 12 volt computer
fan will be close to inaudible.
You can do this trick easily enough
in any PC, by wiring your 12 volt fan to, say, the five volt and ground
wires from your power supply. That's 41.7% of the expected voltage, and
17.4% of the full output power, if, of course, you happen to be living in
Physics Experiment Land where pulleys are frictionless, rope is inelastic
and all cows are perfectly spherical.
In the real world, though, the numbers
will still work out pretty close to what they should be.
If you want some more voltage -
and you probably do, because five volts isn't enough to start some 12 volt
fans spinning, although they'll run OK if you give them a flick-start with
a finger - then connecting the positive fan lead to +12 volts and the negative
lead to +5 volts gives you a quick and dirty seven volt supply. 58.3% voltage,
34% power. You get the idea.
To save you from wire-splicing,
Zalman provide you with this "Quiet Mode Adaptor". It's a little three wire
extension lead with a 55 ohm medium power resistor spliced into the positive
lead. The tachometer lead still works as it did, so the fan can still report
its speed if you're powering it from your motherboard. But it gets a resistor-dropped
supply voltage.
Exactly what that supply voltage
turns out to be depends on the fan's own impedance. The fan the CNPS3100G
kit comes with draws about 200 milliamps (mA) in full-power mode; putting
the resistor in line drops its supply voltage by almost half, and pretty
much exactly halves its current draw. Which means you're getting roughly
quarter power. The resistor gets to dissipate 0.55 watts, and gets noticeably
warm, but that makes no significant difference to anything.
It would make a difference, if you
were using the resistor to drop the voltage to a much higher power fan,
like a seven watt unit. That behaves like a 20.6 ohm resistor as far as
the power supply's concerned, and putting 55 ohms more resistance into the
circuit will still leave you with about a 160mA current draw, which means
the resistor's got to get rid of 1.9 watts. It'll be able to do that, but
it'll probably get hot enough to burn you in the process.
This, by the way, is also the reason
why mechanical speed controllers for radio controlled model cars burn up
when you use them with high power modified motors.
Mind you, things will only work
out properly if the fan actually manages to spin. The lower the fan impedance,
the less of the total potential difference from the power supply it'll get
when it's fed through a given resistor. In the above case, it'd get only
about 3.3 volts, which probably wouldn't be enough to start it.
Thanks for tuning in. Next week
on Electronics In Practice...
Wait. Where was I?
Ah yes. Performance.
With the stock fan running at full
speed and sitting right above the heat sink, the CNPS3100G managed 0.76°C/W.
Not what you'd call thrilling performance, but not bad.
I tried turning the fan so it blew
across the fins rather than down onto them; performance fell a bit, so I
went back to the above-the-sink arrangement.
With the resistor lead in-line,
the standard fan was as silent as Zalman's promotional material said it'd
be. Now the cooler turned in a 0.98°C/W result.
That's not bad, for something that
makes no more noticeable noise than a passive heat sink. If you want a silent
PC with half-decent CPU cooling and you're not an overclocker, the silent-mode
CNPS3100G seems a good option.
The heck with silence for the time
being, though. To see how the FHS would go if it were sitting next to a
blowhole in a modified case with a high power fan blowing onto the CPU area,
I traded the stock fan for a chunky 120mm seven watt Sunon. Now the FHS
turned in a 0.65°C/W result. Which is pretty respectable.
Next, I tried my ferocious little
Y.S. Tech 60mm seven watter, sitting right above the heat sink - and got
0.60°C/W.
Any cooler's performance is dependent
on how much air flow it gets, but the FHS's peculiar design means that this
variable is, well, more variable than usual. It depends on where the fan
is relative to the heat sink, how close the fan ends up being to the side
of the case, and whether or not you're using the in-line resistor. And there's
nothing stopping you using some completely different fan, of course.
With the stock fan running at its
lowest speed, nowhere near a vent in the case, and not quite lined up with
the heat sink, the CNPS3100G can be relied upon to deliver very unexciting
performance. But it'll probably still be fine for a Celeron or slower P-III
machine.
If you give this cooler a ton of
air flow, it performs quite impressively. But if you're after a loud-fan
overclockers' special, you can do better with a cheaper product.
I wouldn't say that this thing is
really the world's highest performance heat sink.
To be fair, Zalman leave themselves
a loophole in their PR puffery. The full quote from their page is actually
"World's highest performance heatsink manufactured by Zalman". So if it's
just the best one they make, then it lives up to the description. Saved
by the fine print.
In any case, the Zalman claims about
the FHS don't hold up even within their own product line. Because they actually
make something better.
