Zerotherm Zen FZ120 CPU Cooler

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The Zerotherm Zen FZ120 is a conventional, high performance, tower heatsink for CPUs — it has four U-shaped heatpipes, tightly packed fins, and a 120mm PWM fan attached via wire clips. It sports a few curves and contours reminiscent of the BTF80/BTF90 “butterfly” coolers (which were quite good)… but the sheer size of the new Zen makes it a more serious contender.

Zerotherm Zen FZ120 CPU Cooler

June 22, 2008 by Lawrence Lee

ZEROtherm Zen FZ120
LGA775 & K8 CPU Cooler
Street Price
~$50 USD

Zerotherm is branded in our minds as the ones responsible for the BTF80
and BTF90
CPU coolers… it’s hard to forget heatsinks shaped
like Butterflies. Fortunately, they turned out to be good performers, and we hope their newest product follows suit. The
Zen FZ120 is a more or less conventional tower heatsink — it has four heatpipes, tightly packed fins, and a 120mm PWM fan attached
via wire clips. However, it does sport a few curves and contours reminiscent of
the BTF80/BTF90.

The box with Intel stock cooler provided for scale.

More often than we like, heatsinks ship with large, unwieldy boxes and
a dreaded plastic blisterpack inside. The Zen however ships in a relatively eco-friendly
compact box without extraneous packaging. It also lacks gaudy artwork on the
outside, presenting itself with very little fanfare. Inside you will find the
heatsink itself, a transparent 120mm fan, a common AMD mounting clip, a LGA775
mounting frame and backplate, fan clips, fan isolation rubber strips, a tube of thermal
grease and instruction guide.


Zerotherm Zen FZ120: Key Features
(from the product
web page
Feature & Brief
Our Comment
Best Performance among
120mm air cooling CPU coolers
To be determined…
Effective 8-line Heat pipe
The Zen’s four U-shaped heatpipes
act as eight.
Honeycomb structure for
optimized air flow.
The fins at the center of the Zen
are out of alignment with the rest of the heatsink, creating an overlapping
honeycomb arrangement.
120mm fan for max. air-flow Standard for modern heatsinks.
(Automatic Fan Control)
A welcome addition. More fans should
have the PWM feature.
Silence Innovations
Min. 19 .5 dBA at 1,100 rpm
Max. 31.4 dBA at 1,800 rpm
As always, specified noise levels
must be taken with a grain of salt.
Support latest Intel & AMD CPUs As it should.
Zerotherm Zen FZ120: Specifications
(from the product
web page
Dimensions 126 X 61 X 156 mm
(4.96 X 2.40 X 6.14 inch)
Weight 670g (Without Clip Components)
Matreials Fin – Aluminum
Base – Copper
Heat Pipe – Copper
Heat Dissipation Area 6,827 cm² (1,058 inch²)
Cooling Capacity Over 150W
Fan Size 120 X 25 mm (4.72 X 0.98 inch)
Fans Speed 1,100 ~ 1,800 rpm (± 10%)
Acoustic Noise Min. 19.5 ~ Max. 31.4 dBA (± 10%)
Connector 4 Pin, PWM
Operating Voltage 5.0 ~ 13.8 VDC
Airflow Rate 59.48 CFM
Zerotherm Zen FZ120: Compatibility
(from the product
web page
Intel CoreTM2 Extreme Socket-T
Support All
Speeds (Models)
CoreTM2 Quad
CoreTM2 Duo
Pentium D
Pentium 4
AMD Phenom X3 / X4 Socket
939 / 940 / AM2
Support All
Speeds (Models)
Athlon64 FX X2 / BE
Incompatibility List
Intel Socket 478, 771, 603, 604
AMD Socket 754, Socket F or
Socket A


The Zen bears a resemblence to the Thermalright
The size and overall shape is very similar.

Zen on the left, Ultra-120 on the right.

Unlike the Ultra-120, the Zen’s heatpipes are positioned in a straight line
rather than staggered, and lack the nickel coating.

The top.

The Zen’s design also has many many twists and turns, both in its interior
and on its exterior. The surface of the heatsink that contacts the fan is contoured,
as are the sides, creating a generally wavy appearance. The way the fins are
shaped create a unique overlapping "honeycomb" pattern in the center.
The fins on the outside curve upward at the center, but in the middle they curve

Fin layout/spacing.

While the interior curvature increases the amount of surface area subject to
direct airflow, it also makes impedance more of a factor, at least at the center.
The fin spacing is already fairly tight at approximately 1.8mm.

From the side.

From the side it’s evident that the Zen is quite narrow, and its fins thin. We measured them to be approximately 0.37 mm thick.


The base and mounting system is vital to the performance of
any heatsink. Without proper contact, the heatsink design is meaningless.

The bottom.

The base and heatpipes are both comprised of copper, and they are clearly joined with solder. This is the only place on the heatsink where solder is visible; the fins, in contrast, appear to be just tightly press-fitted. A mounting plate (made of cast steel or aluminum) sits on top of the base, holding everything in place. No
surprises here.

The base.

The surface of the base was very flat and had a pleasant
gleam. Some very faint circular machine marks were visible.

LGA775 mounting frame installed.

The LGA775 frame is attached via four screws to the mounting
plate. Four spring-loaded screws secure it to a backplate placed on the back
of the mainboard. This does require access to both sides of the motherboard, which means installation on an existing system calls for the motherboard to be removed. It’s more work, but through-the-board bolt mounting is the most secure for any heatsink, especially heavy, tall ones like this Zen.

Installed, with fan.

The Zen installed very easily. An ordinary screwdriver was used to tighten the screws; the fins do not overhang the screws because of their relatively narrow depth. You simply tighten each screw as far as it will go, and the captive spring takes care of the tension. The fit was quite snug, as it should be. The fan is attached via two metal wire clips which are inserted
into holes located on the top and bottom fin on each side. The fan can be
decoupled slightly by strips of rubbery isolation material included in the package.


Measurements of some basic physical attributes have been
added to our test routine.

Zerotherm Zen FZ120s: SPCR Measurements
Weight 610 g (heatsink
640 g (heatsink and mounting frame/screws)
760 g (heatsink, mounting frame/screws, stock fan and accessories)
Fin thickness ~0.37 mm
Fin spacing ~1.80 mm
Vertical Clearance (northbridge) ~43 mm (measured from the
PCB to the furthest reach of the heatsink)
Overhang (PSU) ~12 mm (this
will depend on the distance from the CPU socket to the edge of the PCB)

A comparison of fin thickness and spacing among various tower
heatsinks is interesting. The Zen’s fins are quite thin and spaced tightly.

Comparison: Fin Thickness & Spacing
Fin Thickness
Fin Spacing
Scythe Ninja
0.31 mm
3.95 mm
Thermalright HR-01 Plus
0.45 mm
3.15 mm
Noctua NH-C12P
0.47 mm
2.54 mm
Xigmatek HDT-S1283
0.33 mm
1.96 mm
Zerotherm Zen FZ120
0.37 mm
1.80 mm
Thermalright Ultra-120
0.45 mm
1.42 mm

Testing was done according to our
unique heatsink testing methodology
, and the reference fan was profiled
using our standard fan testing
. A quick summary of the components, tools, and procedures
follows below.

Key Components in Heatsink Test Platform:

  • Intel
    Pentium D 950
    Presler core. TDP of 130W; under our test load, it measures
    78W including efficiency losses in the VRMs.
  • ASUS
    motherboard. A basic microATX board with integrated graphics
    and plenty of room around the CPU socket.
  • Samsung MP0402H
    40GB 2.5" notebook drive
  • 1
    GB stick of Corsair XMS2
    DDR2 memory.
  • FSP Zen 300W
    fanless power supply.
  • Arctic Silver
    : Special fast-curing thermal interface material, designed
    specifically for test labs.
  • Nexus 120 fan (part of our standard testing
    methodology; used when possible with heatsinks that fit 120x25mm fans)
Nexus 120 fan measurements
21 dBA@1m
1100 RPM
18 dBA@1m
890 RPM
16 dBA@1m
720 RPM
<15 dBA@1m
530 RPM

Test Tools

  • Seasonic
    Power Angel
    for measuring AC power at the wall to ensure that the
    heat output remains consistent.
  • Custom-built, four-channel variable DC power supply,
    used to regulate the fan speed during the test.
  • Bruel & Kjaer (B&K) model 2203 Sound Level
    . Used to accurately measure noise down to 20 dBA and below.
  • Various other tools for testing fans, as documented
    in our standard fan testing

Software Tools

  • SpeedFan
    , used to monitor the on-chip thermal sensor. This sensor is not
    calibrated, so results are not universally applicable.
  • CPUBurn
    , used to stress the CPU heavily, generating more heat than most
    real applications. Two instances are used to ensure that both cores are stressed.
  • Throttlewatch
    , used to monitor the throttling feature of the CPU to determine
    when overheating occurs.

Noise measurements were made with the fan powered from the lab’s variable DC
power supply while the rest of the system was off to ensure that system noise
did not skew the measurements.

Load testing was accomplished using CPUBurn to stress
the processor, and the graph function in SpeedFan was used to make sure that
the load temperature was stable for at least ten minutes. The stock fan was
tested at various voltages to represent a good cross-section of its airflow
and noise performance.

The ambient conditions during testing were 15 dBA and 21°C.


Stock Fan Testing

The included stock fan is a clear plastic 120mm fan with a 4-pin PWM connector.
The blade design is similar to Panaflo and Yate Loon fans — the trailing edges
are more or less straight, and pass by the struts at an angle (which is better for reduced tonal noise).

Stock fan.

A sticker on the hub identifies Silentmatic as the manufacturer.

Co. Ltd.
Power Rating0.22A
Model NumberSFA1225MU-12PAirflow Rating59.48 CFM
Bearing TypeSleeveRPM Rating1,100 ~ 1,800 rpm (± 10%)
Hub Size1.58"Noise RatingMin. 19.5 ~ Max. 31.4 dBA (± 10%)
Frame Size120 x 120 x 25 mmHeader Type4-pin PWM
Weight120gStart Voltage4.5V
36 dBA@1m
1860 RPM
25 dBA@1m
800Hz tonal peak
1140 RPM
18 dBA@1m
750 RPM
17 dBA@1m
540 RPM

Fan @ 12V: Very buzzy with lots of chatter, mainly due to vibration.
The chatter lessens if held firmly in free air or properly secured on a heatsink
as opposed to standing unsupported on a hard or soft surface. At 36 dBA, it
is loud and annoying.

Fan @ 9V: Much smoother, with only a slight whine detectable.
The SPL registered at 25 dBA with a tonal peak at 800Hz.

Fan @ 8V: The noise level was reduced to a gentle hum. It’s quiet and unobtrusive.

Fan @ 7V: The fan is effectively silent. It sounded very
smooth with some clicking evident at close range.

Overall, it behaves more or less typically for a sleeve bearing PWM fan. Its
acoustics are lousy at full speed, but when undervolted, it quiets down nicely.

Cooling Results

Zereotherm Zen FZ120 w/ stock fan
Fan Voltage
Noise @1m
°C Rise
36 dBA
25 dBA
19 dBA
17 dBA
Zereotherm Zen FZ120 w/ reference Nexus fan
21 dBA
18 dBA
16 dBA
<15 dBA
Load Temp: CPUBurn for ~10 mins.
°C Rise: Temperature rise above ambient (21°C) at load.
°C/W: based on the amount of heat dissipated by the CPU (measured
78W); lower is better.

Zen performed extremely well with the stock fan, especially at higher speeds
— the rise above ambient was only 12°C and 15°C with the fan at 12V and
9V respectively. Performance dropped off significantly when the fan voltage
was lowered most likely due to tight fin spacing.

Switching to our reference Nexus fan dramatically improved the performance-to-noise
ratio. It managed to deliver approximately the same level of cooling at each voltage setting, but with
much less noise. For example, when both fans were set to 7V, the Nexus fan registered
1 dBA lower, yet still managed to deliver a 6°C improvement in CPU temperature.


Comparison: Zen vs. Top Heatsinks w/ Reference Nexus Fan
Fan Voltage
Noise @1m
°C Rise
HR-01 Plus
Ultra-120 eXtreme
Zen FZ120
Ninja Copper
21 dBA
18 dBA
16 dBA
<15 dBA

Against the competition, the Zerotherm Zen performed well enough to take
the number four spot, slightly edging out the Scythe
Ninja Copper
. While it is only about two degrees off our new favorite,
the Thermalright HR-01 Plus,
its tight fin spacing becomes an issue when the airflow is lowered to extreme
levels. Like the Xigmatek
and Ultra-120
, the Zen takes a sizable performance hit when the Nexus fan
is slowed from 7V to 5V.


The recording begins with a six second stretch of the ambient noise of the test
room. This is followed by 10 seconds at each voltage level. Please set your playback volume so that the ambient noise is almost inaudible,
then don’t adjust the volume control again. For best results, save the sound
file to your own PC, then listen.

Zerotherm Zen FZ120 with stock
fan at 7V, 8V, 9V and 12V at 1m
(Watch out for the 12V level; it’s noisy!)

Reference Comparatives

"Real Silent 120mm fan"
(at 5V, 7V, 9V and 12V at 1m)


The Zerotherm Zen FZ120 is a formidable CPU cooler. Not only does it perform
well, its mounting system is secure, and the installation procedure is straightforward.
There is no need to fiddle around with various sets of screws, wings, nuts,
washers or other doo-dads — manual dexterity is taken out of the equation.
It’s also an all-in-one solution, as a fan with PWM functionality is included.

The fan is a weak point. It is a fairly
typical stock fan — loud at full speed, with mediocre acoustic quality.
Fortunately, lowering the fan speed should be easy since almost all current motherboards sport PWM fan speed control. When slowed
to 700 RPM or lower, it is quiet enough for most users. While it doesn’t perform as well as
our reference Nexus fan, that is not unusual. Fan selection is usually an afterthought
for most manufacturers, and they tend to choose high airflow capability over best acoustics.

Overall, the Zen is an excellent heatsink with few surprises. Its US$50 price tag is pretty good unless you’re not satisfied with the stock fan. But at least one of SPCR’s affiliate online stores is selling it for as low as $40, which is an excellent deal.

Zerotherm Zen FZ120

* Great performance
* Easy, secure mounting system
* PWM fan included
* Stock fan decently quiet when run slower


* Included fan too loud at full speed

Our thanks to ZEROtherm
for the Zen heatsink sample.

* * *

Articles of Related Interest
Noctua NH-C12P: A Top-Down Cooler Rises Up
HR-01 Plus: 2nd Gen Killer Tower Cooler

Zipang 14cm fan "blow-down" CPU cooler

Cooler Master Hyper Z600
CPU Cooler: A Real Heavyweight

Intel’s HSF for high-end
Core 2 Extreme CPU cooler

Thermaltake V1: "Peacock
Tail" Cooler

* * *

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