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Zalman CNPS9500 LED heatsink/fan

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It’s hard to believe, but the 9500 is Zalman’s first CPU heatsink to use heatpipes. They’re no strangers to heatpipes, having used them in many other cooling devices, such as VGA and HDD coolers; never before in a CPU cooler, though. But the waiting might have been worthwhile. The CNPS9500 could be the most sophisticated implementation of a heatpipe HSF for CPUs we’ve ever seen.

Sept 12, 2005 by Devon
Cooke
with Mike Chin

Product
Zalman CNPS9500 LED CPU Heatsink
for socket 478 / 754 / 775 / 940 / 939
Supplier
Zalman Tech. Co.,
Ltd.
Price
~US$75

Zalman made a name for itself with highly efficient CPU heatsinks
that work well with low airflow ? an excellent combination for low noise.
Their original “flower” design was a stroke of genuis: Many thin fins clamped very tightly together along one edge, which was then machined to a fine polish to become the base. The unattached opposite ends of the fins was spread apart to allow airflow between them. At the time, it was an inexpensive way to make a very high performance heatsink. It spawned many copycats, and several
other companies adopted similar designs. Imitation may be the sincerest
form of flattery, but it is probably keeping Zalman’s patent lawyers busy.

We’ve recommended the Zalman CNPS7000 series for over two years, but that model
has begun to show its age. There are now more efficient, less expensive heatsinks
available. Zalman has not been resting on its laurels; they displayed
their newest heatsink, the CNPS9500, at Computex in May 2005. It is now
September and the new model is beginning to find its way into the retail market, although
it is still hard to find. Zalman finally added the
product page for the 9500 to their web site
just days before this article was posted.

The Zalman 7000 series (and the similar 7700 series) were top performers when they were first released, but they lack one technological feature
that competitors have been integrating for some time: Heatpipes. Zalman is no stranger to heatpipes. They have been using heatpipes in many products, including their video card coolers, and the massive fanless TNN series cases, which make extensive use of heatpipes. The 9500 is their first CPU heatsink to use heatpipes. It takes the highly efficient
flower design of the earlier Zalman heatsinks, adds three heatpipes, and tilts the fin configuration 90 degrees so that the fan blows across the motherboard rather than down at it. The
surface area of the heatsink fins (the “flower petals”) has been
increased, as the flower is now elevated above the motherboard where it will
not interfere with the other components. It looks like a “stem”
has been added to the flower.


The box is large and retail-friendly with a plastic window that lets you
see the product.


The box lists the specifications. It’s quite light for an all-copper design.


The usual Zalman accessories, including Fanmate 2 to control
fan speed.

Zalman CNPS9500: Feature Highlights (from the product
box )

Feature & Brief Our Comment

Minimized Weight
Optimized heatsink layout for maximum cooling efficiency with minimal
materials.
0.2mm ultra slim fins for minimized weight and reduced airflow resistance.

Weighs 530g, just 80g over the max recommended 450g specified by Intel and AMD. Low weight is especially important because
the tower design means the cantilever force on the motherboard will be
quite high.

Ultimate Performance
100% copper heatsink with aerodynamically optimized “tunnel”
design for maximum cooling efficiency.
Innovative patented heatpipe bending design for heat transfer capacity
of up to six heatpipes with just three heatpipes.

Three heatpipes are used,
but heat is transferred from the ends of the heatpipe to the middle rather
than from one end to the other.

Ultra Quiet Operation
Ultra Quiet CNPS 92mm opaque fan with blue LEDs.
Aerodynamically optimized heatsink for smooth airflow and minimal noise.

Not quite “opaque”, but not quite transparent either. The
fan blades are “frosted”: They allow light to pass but do not
allow a clear line of sight. Blue LEDs. Bling.

Broad Compatibility
Intel: All Dual Core Pentium CPUs (Socket 775)
All Pentium 4 CPUs (Socket 775/478)
AMD: All Dual Core AMD Athlon 64 X2 CPUs (Socket 939)
All AMD Sempron / AMD64 CPUs (Socket 754/939/940)

Only Socket A is missing.
Funny how they don’t mention Celeron CPUs…

DESIGN DETAILS

The basic design of the CNPS9500 is a Zalman 7000 turned
sideways and perched on heatpipes. The design is a good one: Embedding the fan
inside the heatsink allows every bit of airflow from the fan blades to dissipate
heat.


The CNPS9500 is a clever evolution of the CNPS7000 design.

The diameter of the “flower” is the same as the Zalman
7000 series, and a similar 92mm fan is used. Like the 7000, the flower is
incomplete; roughly a sixth of the circumference is left open to leave room
for the heatpipes. The fins are bigger than the ones on the 7000,
so the total surface area of the fins ? and the cooling potential ?
is greater. It has the biggest cooling surface area of any Zalman HS: Zalman cites 3,698 cm2 for the 9500. The 7000 series heatsinks come in at 3,170 cm2, and the 7700 is 3,268 cm2.


The CNPS9500 turns the design sideways and elevates it above the motherboard
where there is less chance of interfering with the other components.

MODEST WEIGHT

The 9500 weighs only 530 grams, compared to 775 grams for the all-copper
7000cu or 918 grams for the 7700cu. The difference is the “tunnel” through the center of the 9500, which is devoid of any metal.
In the 7000 and 7700 series, this center forms the solid, massive base. In comparison, the base on the 9500 is a small copper plate and an aluminum top plate with the heatpipes clamped between them. Aside from the weight reduction, a second advantage of this design is that air flows
through the heatsink with little impedance. This means that all of the fin surface area can work efficiently to dissipate heat, and there is very little ineffectrive turbulence cause by sharp angle turns in airflow direction.


The center is hollow, allowing air to pass.

COOLING FOR VRMs

Unlike most “tower” style heatsinks with fans that blow
across the motherboard, airflow is not ducted from one end
of the heatsink to the other. Instead, air can escape from all sides, including
the top and bottom. This means that a substantial amount of air should end up being
blown down towards the VRMs (Voltage Regulation Modules) that usually surround
the CPU socket, cooling them in the process. This is important, as ATX motherboards
are designed with this kind of cooling in mind; many tower-style heatsinks risk
shortening the life of the motherboard because they tend to block the airflow from reaching
these components.

The fins are anchored to three heatpipes that rise gracefully
up from the base in a figure 8. The fins are attached to the middle of the
heatpipes, while both ends are attached to the base. The flow of heat inside
the heatpipes is from the ends to the middle.


Both ends of each heatpipe are attached to the base and rise up in a figure
eight.

Zalman has made excellent use of the heatpipes. The distance from a
heatpipe to the edge of a fin is never much more than a couple centimeters,
which means that there are no “dead spots” on the fins; just as the
embedded fan spreads the airflow evenly across the fins, the heat is also evenly
distributed.

INTEGRATED FAN


The fan, looking up from the bottom of the heatsink.

The LED fan is mounted on a steel bracket that positions it just above the
top of the fins. On our sample, the fan was slightly off-center. This has no
practical downside, but it suggests that the manufacturing process by which
the heatpipes are formed probably isn’t quite perfect yet.

The fan blows through the heatsink, so care should be taken to install the
heatsink in the right orientation. The mounting system allows the 9500 to be installed “facing” any of four directions. Ideally, the empty side of the heatsink should face
the rear case fan, so that the hot air coming off the heatsink is immediately
exhausted.

Zalman rates the fan at 0.35A and 2600 RPM, quite high for a fan that is supposed
to be quiet. In comparison, the 92mm fan in the 7000 series is rated for 0.23A
and 2400 RPM. It is also a dual ball-bearing fan, which is usually not the best
choice for noise, although a quieter sleeve-bearing fan would not be as reliable
for use in a high-heat application like a heatsink. As with all their CPU heatsinks,
Zalman ships a Fanmate 2 fan controller with the CNPS9500, so the fan can be
easily undervolted down as low as 5V.

INSTALLATION

Installation hardware is included for sockets 478, 775 and K8. A backplate is included for use with motherboards that do not already
have one. A heatsink retention module is also included for use with Socket 775
systems. As usual, Zalman has a nicely illustrated instruction sheet, as well as a good animated flash version of the installation on the product web page.

Socket 478 systems can take advantage of the stock heatsink retention module,
thanks to two aluminum yoke-shaped anchors that lock into place. They are similar
but not identical to those used with the Zalman 7000 and 7700 series of
heatsinks, and work in a similar way. The difference? The 9500 anchors are lower
profile and use a finer thread for the screw hole.


In front, the clips for the CNPS9500. Behind, the clips for the CNPS7000.
Both the height and the screw thread are different.

Once the proper hardware has been attached to the motherboard, installation
is pretty much the same for all platforms. A retention clip is placed over
a “hub” in the center of the heatsink, and the two ends of the clip
are screwed to the hardware that has been attached to the motherboard. The screws
for each platform are different, so pay attention to the instruction manual.
They also have a hexagonal head, so the included Allen key must be used to tighten
them. Because the fins overhang the screws, it is easiest to use the ball-shaped
end of the Allen key which lets the shaft of the key be at a slight angle to
the head of the screw.


The mounting bracket fits over the hub in the center of the base.

The orientation of the CNPS9500 can be changed depending on whether the clip
is installed through the heatpipes or between them. The proper orientation should
direct the airflow of the integrated fan towards the rear of the case. For our socket 478 motherboard, the proper configuration required the clip to be positioned between the heatpipes. This task was quite difficult. It took us about 10 minutes of fiddling to maneuver it into position without
using force. The bracket must be slipped in between the heatpipes sideways and
then rotated to horizontal position so that it fits over the center hub. The
problem is that the bracket almost always catches on either the hub or the heatpipes
above it when it is rotated. A small adjustment in production would probably eliminate this annoyance. NOTE: Later attempts at doing this proved more successfully. The trick is to apply a little force as you rotate the clip, jiggling the piece as you rotate it.


Installing the clip between the heatpipes is a finicky task.


Mounting the clip this way is a cinch.

The heatsink should be installed outside the case if possible. It is probably impossible to install it inside a case, as the fins hang
over the screw and requires access to
the sides of the motherboard in order to be tightened.

The heatsink is also quite large; it hung over the top edge of our test motherboard. This may cause compatibility problems in cases where the gap between
power supply and the top edge of the motherboard is small. Obviously, boards that position
the CPU socket closer to the center of the board will not have this problem,
although if the socket is too low, the heatsink could interfere with video
cards that have a large heatsink.


The fins hang over the edge of our test board.

TESTING

Test Platform

  • Intel
    P4-2.8A
    The Thermal Design Power of this P4-2.8 (533
    MHz bus) is 68.4 or 69.7W depending on the version. As the CPU is a demo model
    without normal markings, it’s not clear which version it is, so we’ll round
    the number off to ~69W. The Maximum Power, as calculated by
    CPUHeat
    & CPUMSR
    , is 79W.
  • AOpen
    AX4GE Max
    motherboard – Intel 845GE Chipset; built-in VGA. The on-die
    CPU thermal diode monitoring system reads 2°C too high, so all readings
    are compensated up by this amount.
  • OCZ
    DDRAM
    PC-3200, 512 MB
  • Seagate Barracuda IV 40G 1-platter drive (in Smart
    Drive
    from Silicon
    Acoustics
    )
  • Seasonic
    Super Tornado 300
    (Rev. A1)
  • Arctic Silver
    Ceramique
    Thermal Compound
  • Nexus 120 fan
  • Two-level plywood platform with foam damping feet. Motherboard on
    top; most other components below. Eases heatsink changes and setup.

Measurement & Analysis Tools

  • CPUBurn
    processor stress software
  • Speed Fan
    software to show CPU temperature
  • A custom-built fan controller that allows us to dial in the precise voltage
    to the fan
  • Electronic Anenometer (to measure fan air flow)

Noise measurements were made with the fan powered from the fan controller while
the rest of the system was off to ensure that system noise did not skew the
measurements. Because the CNPS9500 is sold as an integrated unit with both the
heatsink and fan installed, it was tested with the stock fan instead of our
usual reference fans.

The ambient conditions during testing were 19 dBA and 26°C. This is about five degrees warmer that
is usual in our lab.

TEST RESULTS

Zalman CNPS9500 with Stock
Fan
Fan Voltage
Airspeed
Load Temp
°C Rise
°C/W MP
°C/W TDP
Noise
12V
25 CFM
40°C
14
0.18
0.20
37 dBA/1m
9V
20 CFM
41°C
15
0.19
0.22
32 dBA/1m
7V
16 CFM
42°C
16
0.20
0.23
27 dBA/1m
5V
11 CFM
44°C
18
0.23
0.26
22 dBA/1m

Airspeed: Amount of airflow, measured in Cubic Feet
per Minute. NOTE: Zalman’s specs for CFM were likely taken in free air; ours were taken with the fan mounted in the HS, which means it’s facing more restrictions. Hence the lower numbers.
Load Temp:
CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient at load.
°C/W MP / TDP: Temperature rise per Watt, based on CPU’s Maximum
Power (79W) or Thermal Design Power (69W) rating (lower is better)
Noise: SPL measured in dBA/1m distance with high accuracy B &
K SLM

12V / 25 CFM: The cooling performance is excellent, on par with the
best we’ve measured. However, the noise level is terrible, with a large amount
of turbulence noise and motor whine. The quality of the noise aside, it’s
simply too loud. 37 dBA/1m will be heard plainly no matter how well damped the case.

9V / 20 CFM: Performance continues to be very good. In fact, there’s only
a single degree increase compared to the 12V test. Noise
drops significantly, although it is still too loud for quiet PC.
As before, air turbulence dominates the noise character, although the underlying
noise of the bearings and the fan motor can also be heard.

7V / 16 CFM: Here, the fan becomes borderline quiet. This level of
noise is probably acceptable in a high performance rig where other components
produce too much heat to be cooled more quietly. The whine of the motor is
now the predominant source of noise; air turbulence is in second place. Performance
is still excellent, dropping only two degrees from 12V.

5V / 11 CFM: The fan drops to a reasonable 22 dBA/1m. This should
be quiet enough for many people, although those with low ambient noise may
want quieter. A surprising amount of motor noise is still audible
as a mid-band hum, and a low buzz from the bearings can also be heard during
close listening. Performance is only four degrees off the 12V level. This
is exceptional performance with low airflow; many heatsinks lose between 10-15°C
of performance when undervolted to 5V.

There is still a considerable performance headroom for quieter operation.
This could be achieved through a fan swap (an involved process that requires
some handiness), or by further undervolting. The stock fan starts reliably
below 4V, although it is difficult to obtain this voltage without DIY skills
in electronics.

COMPARISONS

The performance of the Zalman 9500 was compared with its obvious competitors: The
Scythe Ninja
and Thermalright
XP-120
, currently at the top of our recommended HS list. For good measure, the original Zalman 7000ALCU was also thrown into
the mix.

Two comparisons were made:

  • One with constant airflow so we could
    judge the pure thermal efficiency of the heatsink itself;
  • One with constant noise
    to determine which is best for use in a quiet computer.

Data for this
comparison was drawn from the reviews linked to above. All of these reviews
use the same testing platform, so measurements are comparable.

Heatsink Comparison at Similar Airflow speed
Heatsink
CFM
°C Rise
°C/W MP
°C/W TDP
Noise
Zalman 9500
25
14
0.18
0.20
37 dBA/1m
Zalman 7000ALCU
23
20
0.25
0.29
39 dBA/1m
Scythe Ninja
22*
19
0.24
0.28
<18 dBA/1m
(Nexus fan @ 7V)
Thermalright XP-120
25*
19
0.24
0.28
23 dBA/1m
(Globe fan @ 6.8V)

*The Nexus fan CFM was measured directly on the Ninja HS for this comparison.

The Globe fan CFM was measured directly on the XP-120 in the previous 7700 review.

The table above makes it quite clear how good the Zalman 9500 is: At roughly
the same airflow it significantly outperforms every other heatsink we’ve tested.
However, that is only part of the story. At the tested level of airflow, the
Zalman 9500 is far too loud for use in a conventional case. The heatsinks that
use 120mm fans have the advantage here because they have a much better noise
/ airflow ratio than the smaller 92mm fan in the Zalman heatsinks.

Ranking the heatsinks by noise produces a different result, although this is
not quite a fair comparison because we were able to choose our favorite 120mm
fans for the Ninja and XP-120, while the two Zalman heatsinks were tested with
their stock fans.

Heatsink Comparison by Noise
Heatsink
Noise
°C Rise
°C/W MP
°C/W TDP
CFM
Zalman CNPS9500
22 dBA/1m (5V)
18
0.23
0.26
11
Zalman CNPS7000ALCU
22 dBA/1m
27
0.34
0.39
8
Scythe Ninja
22 dBA/1m
(Nexus fan @ 12V)
14
0.18
0.20
31*
Thermalright XP-120
23 dBA/1m
(Globe fan @ 6.8V)
19
0.24
0.28
25*

*The Nexus fan CFM was measured directly on the Ninja HS for this comparison.

The Globe fan CFM was measured directly on the XP-120 in the previous 7700 review.

When the noise level is held constant, the clear winner is the Scythe Ninja,
thanks to the quiet 120mm Nexus fan that was chosen. The Zalman 9500 is roughly
on par with the XP-120, while the Zalman 7000 is simply not in the same league.

However, holding noise constant does not tell the whole story, either. At 22 dBA/1m,
the Zalman 9500 is the quietest it can be in stock form; it is not possible
to undervolt its fan any further without resorting to DIY solutions. By contrast, the fan on the Ninja is
running at full speed at this level and can easily be undervolted down to below 18
dBA/1m.

It’s safe to say that the Zalman 9500 is the most efficient of all heatsinks that use a 92mm fan. The basic design is brilliant, but it cannot completely escape the limitation of fan size. The blades of a typical 92mm fan has only a little more than half the area of those on a 120mm fan. The Scythe Ninja does better at a lower noise level because it has similar fin surface area and can be used with a quieter, larger fan. A quieter fan on the 9500 fan would certainly help, but we suspect it would still not match the Ninja for cooling performance at very low noise levels, simply because the airflow would always be lower because of the smaller fan.

NOISE RECORDINGS

Zalman CNPS9500 integrated heatsink/fan:

MP3:
Zalman CNPS9500 – 9V – 20 CFM / 33 dBA/1m

MP3:
Zalman CNPS9500 – 7V – 16 CFM / 28 dBA/1m

MP3:
Zalman CNPS9500 – 5V – 11 CFM / 23 dBA/1m

The 9500 at 12V was not recorded, because at 37 dBA/1m, it’s simply too loud; there’s no point.

Recordings of Comparable HSF:

MP3: Zalman
CNPS7000 – 5V – 22 dBA/1m

MP3: Zalman
CNPS7700 – 5V – 22 dBA/1m

MP3: Arctic
Cooling Super Silent 4 Ultra TC, 22 dBA/1m

MP3:
Arctic Cooling Freezer 4 – 7V – 20 dBA/1m

HOW TO LISTEN & COMPARE

These recordings were made with a high
resolution studio quality digital recording system. The microphone was 3″ from
the edge of the fan frame at a 45° angle, facing the intake side of the fan to
avoid direct wind noise. The ambient noise during all recordings was 18 dBA or
lower. It is best to download the sound files to your computer before listening.

To set the volume to a realistic level (similar to the original), try playing this Nexus 92mm case fan @ 5V (17 dBA/1m)

recording and set the volume so that it is barely audible. Then don’t
reset the volume and play the other sound files. Of course, all tone
controls and other effects should be turned off or set to neutral. For
full details on how to calibrate your sound system playback level to
get the most valid listening comparison, please see the yellow text box
entitled Listen to
the Fans
on page four of the article
SPCR’s Test / Sound Lab: A Short Tour.

FINAL CONCLUSIONS

The Zalman 9500 provides excellent cooling performance, close to the best
that we’ve tested, the Scythe
Ninja
, and matches the Thermalright
XP-120
. It provides this performance even
when airflow is reduced by undervolting the fan with the included Fanmate, a feature for which we’ve long applauded Zalman.

However, similar performance could be achieved at a lower noise level with
the two heatsinks mentioned above by using a quiet Nexus 120mm fan. By contrast,
the fan in the 9500 is a step backwards even from its predecessor, the Zalman
7000, which sounded nicer (if only slightly quieter) at the same voltage.

The performance of the heatsink, especially under low-airflow conditions, makes
it an prime candidate for a fan swap. This is a more
difficult procedure than a standard fan swap, but the results are likely to
be well worth the effort. It’s been done with both the Zalman 7000 and the 7700 series.

The wide range of supported platforms is in keeping with most other high-end heatsinks
on the market today, and it is a valuable feature. Including installation
hardware for all major sockets reduces confusion at the store and makes it easier
for the retailer to stock the models you need.

The good airflow to the area around the CPU socket is not to be underestimated, especially for hot running CPUs. Keeping the voltage regulators on the motherboard cool is considered by Intel and AMD to be one of the key roles provided by the CPU heatsink/fan. The 9500 does this well even with low fan speed, despite its parallel-to-motherboard airflow path. Typical HS with this type of airflow have fins parallel to the motherboard that prevent any of the airflow from the fan from reaching the motherboard. The Ninja is a good example of this type of design. It is not conducive to good cooling for the voltage regulators. This is not a big deal for lower power CPUs, but definitely an issue with hotter ones. The price for poorly cooled voltage regulators is high temperatures around the CPU, reduced efficiency, and shortened motherboard life.

Compatibility may be improved over the original 7000 series, since
the bulk of the heatsink is now elevated above the socket. However, the large
size of the heatsink could still interfere with the power supply if the CPU socket is
located near the top of your motherboard. Installation is straightforward as long as you read the directions and use
the proper hardware for your motherboard, but it could take a fair amount of effort, especially if you need to remove the motherboard from
the case. Slipping the mounting bracket between the heatpipes is also more
trouble than it should have been.

All in all, the CNPS9500 is an excellent performing heatsink that rivals
the best and will be at home even in the most powerful gaming systems.
Although it is more expensive than either the Scythe Ninja or the Thermalright
XP-120, keep in mind that neither of these includes either a fan or a
fan controller. The CNPS9500 includes both of these, making it more complete
and user friendly.

Pros

* Top-notch cooling performance
* Support for all recent CPU platforms
* Excellent low-airflow performance
* Included fan controller
* Low weight for an all-copper design

Cons

* Fan could be quieter
* Pricy
* Too big for some cases
* Complex Installation

Much thanks to Zalman
Tech.
for the CNPS9500 sample.

* * *

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