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Thermalright HR-01 CPU Heatsink

From one of the established cooling powerhouses comes a new tall heatpipe heatsink positioned as a fanless, passive cooling device. Sound familiar? Thermalright’s HR-01 is a bit late to the tower HS game… but it certainly has game.

December 22, 2005 by Devon

Thermalright HR-01
K8 compatible CPU heatsink
P4-478 Heatsink Retention Kit
Adapter to allow Socket 478 compatibility
~US$50 (Heatsink) / ~US$4 (S478

Thermalright has been making heatsinks for a long time, and several of its
past models have been SPCR favorites. In the past year or so, their
offerings have been overshadowed by several newcomers, notably the
gigantic Scythe Ninja
that is designed for passive cooling. Thermalright
has responded with a suitably massive and passive tower heatsink of their own: The HR-01.

The first glimpse of the HR-01 leaves no doubt that Thermalright intends to
compete with Scythe (and anyone else using a tower configuration). The heatsink is tall, uses widely spaced fins, and has
heatpipes aplenty. In other words, it looks like a similar, serious competitor. Unless
Thermalright has done something seriously wrong, we can expect it to put up
a good fight.

A plain cardboard box holds the HR-01 inside. (Mouse shown for scale.)

Thermalright eschews fancy retail packaging and has stuck with a plain,
sturdy, corrugated cardboard box. Thermalright’s confidence shines through here: They don’t need
impulse buys based on appearance alone; they know that their customers will
ask for the HR-01 by name. On the other hand it’s the same style of packaging they’ve been using for over four years now, so it’s a tradition, which happens to be environmentally
friendly. It may also be that much of their sales come from online retailers who have little need for visual packaging but do need good shipping protection.

Whatever the rationale behind the plain box, the HR-01 is certainly well packaged.
It lies nestled in a bed of foam that holds it firmly in place. The box is snugly
packed, and there is little chance of the heatsink shifting during transit.

Now that’s a well protected heatsink.

Thermalright HR-01: Feature Highlights (from the
product web page
Feature & Brief Our Comment
Fanless design for low-noise operation
Fanless is definitely low-noise, but
requires good system design to pull off properly.
Proprietary through holes on fins for efficient ventilation
Helps the heatsink take advantage of
system airflow.
Multiple heatpipes for well spread heat around aluminum fins
Four U-shaped heatpipes (for a total of eight heat paths) should be plenty.
Soldered fins to copper base (nickel plated) to make effective
Soldered fins may transfer heat more
efficiently than press-fitted fins.
Light weight and easy installation
Past Thermalright products have been tricky to install; we hope this
one is better.
Thermalright HR-01 Specifications (from the
product web page
Heatsink Dimensions (L × W × H)
110 × 60 × 159.5 mm
525 g
Motherboard Compatibility
Athlon64 FX 3200+ (socket 939/940) and above
Athlon64 3200+ (socket 754) and above
Motherboard Compatibility
Pentium-4 socket 478 up to 3.2 GHz
(Require P4-478
Heatsink Retention Kit

In its stock form, the HR-01 is compatible only with AMD-based motherboards.
This seems to be intentional. It’s well known that AMD CPUs run cooler than
Intel-based CPUs, so naturally they are better suited to passive cooling. Let’s
put that another way: Unless you are a very skilled system builder, you probably
won’t be able to cool an Intel processor passively.

The exceptions to this general rule are Intel’s previous generation of CPUs,
the P4-Northwood chips. Because these chips are compatible almost
exclusively with the now out-of-date Socket 478, Thermalright has chosen to
release an optional Retention Kit that allows the HR-01 to be installed on a
Socket 478 motherboard.

At the time of writing, there is no equivalent Retention Kit for Socket 775,
which means that none of Intel’s current CPUs are supported. However, the
FAQ for the HR-01
lists an appropriate part as “Coming Soon”,
so there may be hope for compatibility some time in the future.


The HR-01 resembles a shiny, postmodern apartment block from
the ’70s. The resemblance may not be intentional, but Thermalright is perfectly
aware of it: The promotional image on the
product page
refers to the HR-01 as “High-Riser”. (What did you
think HR stands for anyway?)

High-Riser is a good description: The heatsink is very tall.
At nearly 16cm, it’s even taller than the Scythe Ninja, edging it out by about a centimeter.
This could pose a problem in narrow cases.

The skyscraper of heatsinks.

The sheer size of the High-Riser almost guarantees that it will perform well,
but it takes more than just size to make a passive heatsink. Other factors are
just as important. For example, the fins need to be spaced widely enough that
the existing system airflow can move heat away from them. Thermalright has done
this, so we have no complaints in this department either.

The fins themselves are quite thick — thicker than they need to be. Although
this keeps the High-Riser quite rigid, it also means the fins could be spaced
a touch further apart if they were thinner. More importantly, the thickness adds a significant amount of

In comparison to other aftermarket heatsinks, the 525 gram weight is fairly
modest, but still exceeds the 450 gram limit that is recommended by both AMD
and Intel. And, thanks to the extremely tall design, this modest amount of weight
still puts a lot of torsion on the motherboard.

31 widely spaced fins provide ample surface area for heat dissipation.

Because the High-Riser is meant to be used passively, the air that cools it
will not be forced from one end of the fins to the other as it would in a conventional
heatsink. Instead, it will take the path of least resistance. Most of the airflow
can be expected to occur around the edges of the heatsink where there is less

Thermalright has done two things to take advantage of this situation:

  1. Every fin is punctured with about fifty holes that allow
    air to travel through the fins themselves as well as between them. This
    helps the heatsink deal with situations where the system airflow is not parallel
    to the surface of the fins. It also lowers impedance as air tries to pass between the fins.
  2. The heatpipes are clustered along the sides of the fins where airflow
    is likely to be strongest. Heat will be transferred away from the heatpipes
    quickly, ideally before it has a chance to saturate the heat capacity of the

The fins are pockmarked with ventilation holes to encourage airflow in all
three dimensions.


Our standard test bench uses a Socket 478 processor, so Thermalright provided
us with the optional P4-478 Heatsink Retention Kit so we could mount it. Thermalright
provides official instructions for how to install the High-Riser on both Socket
and K8-based

Regardless of the platform, the installation process is pretty much
the same. The only difference is which clip you use to secure the heatsink.

First (of course), a layer of thermal grease is applied to the base of the
heatsink. The base is nickel-plated copper. The base
on our sample was smooth and flat. Oddly, the nickel-plating seemed to have
a fine grain to it, as though it had been lapped on fine sandpaper.

A smooth, nickel-plated base makes for good heat conduction.

Once the thermal grease is applied, the heatsink is placed upright on top of
the CPU. There is a small indentation in the center of the base where the clip
applies pressure to the heatsink. The design is quite elegant: It ensures that
the heatsink is aligned correctly over the processor while making sure that
the pressure from the clip is evenly distributed across the base.

The indentation in the center is the sole point of contact between the clip
and the heatsink.

No matter which clip is used, the final step is quite simple: The clip is threaded
between the fins and the base, hooked into the existing retention bracket on
the motherboard, and tightened according to the type of clip. The entire process
takes less than a minute.

Everything needed for installation is included: The K8 clip, and a generously-sized
tube of thermal goop.

The Socket 478 clip requires one extra step, as the clip is shipped unassembled.
Assembly consists of screwing the arms onto the base of the clip and takes an
extra thirty seconds.

Everything that comes in the P4-478 Heatsink Retention Kit.

The clip fully assembled.

One small complaint is that the High-Riser has no provision for installing
a fan. This might be a petty complaint for a heatsink that is supposed to
be passive, but it’s obviously one that Thermalright anticipates. The
FAQ has one question on it: “I have a HR-01 and I would like to install
a 12cm fan on it. Is there a fan wire clip that can be purchased?”

At the time of writing, Thermalright does not supply a fan clip — there’s
nowhere on the heatsink to attach it anyway. Instead, they recommend using cable
ties to attach the fan.

The large size of the High-Riser was not a problem on our test
board, as the fins are a suitable height above the base. It is fortunate that
the heatsink happens to fit with its long edge parallel with the top of the
motherboard. Turned 90 degrees, the side of the heatsink would extend above
the top edge of the motherboard, potentially causing a compatibility problem.

This orientation would also give a performance advantage when the High-Riser
is installed without a fan on it in a system, as the heat will not have as far to travel
between the bottom and the top of the fins. It also works well with Thermalright’s
recommendation that a power supply with a bottom-mounted fan be used to draw
air up through the heatsink.


On the test bench. Note that the position of the 120mm fan allows some airflow
to be deflected down to the board level.
This can be important for cooling of the voltage regulator components around
the CPU socket.

Test Platform

  • Intel
    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
    & 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
  • Seasonic
    Super Tornado 300
    (Rev. A1)
  • Arctic Silver
    Thermal Compound
  • Nexus
    Real Silent
    120mm 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
  • SpeedFan
    version 4.25
    software to show CPU temperature
  • A custom-built fan controller that allows us to dial in exactly what voltage
    is powering the fan
  • B&K model 1613 sound level meter

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 ambient conditions during testing were 18 dBA and 20°C.


As per the design of the High-Riser, our initial testing was done completely
passively, without a fan. This is an extremely difficult situation because passive
heatsinks are designed to take advantage of system airflow. Our test bench,
however, has no system airflow at all. Furthermore, its horizontal
orientation means that the heatsink can’t even use convection cooling, where
airflow is generated by rising heat.

Not surprisingly, the processor quickly shot up to 67°C and began to throttle.
In this respect, it is no different from the Scythe Ninja, which is also designed
for passive use. However, before strapped a fan on, we decided to give the High-Riser
a second chance, this time in a vertical orientation so that it could take advantage
of convection cooling. But, even this configuration did not prevent the processor
from throttling.

The test bench was tilted sideways to see if it could perform passively —
it couldn’t.
It would be wise to rig up some kind of support to hold up the far end of this
A cable tie or stiff insulated wire to the PSU might do it.

Because our test bench does not closely simulate an actual system, in which there would always be peripheral airflow around the CPU area from other fans, such as the back case exhaust fan and the PSU fan. So, we
decided to attach our usual 120 mm reference fan, a Nexus. Testing proceeded
as usual, with measurements taken with the fan at 12V, 9V, 7V, and 5V.

Thermalright HR-01 with Nexus
120 mm fan
Fan Voltage
Load Temp
°C Rise
CPU Throttled
CPU Throttled
22 dBA@1m
~19 dBA@1m
<17 dBA@1m
<17 dBA@1m
Airflow: Measured in Cubic Feet per Minute mounted
on the HS

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 &

The noise profile for the Nexus reference fan is well known, so details about
the noise it makes will not be reproduced here. In any case, it was added for
testing purposes only; in an actual system it would probably not be needed.
In summary: It produces a smooth, quiet hum at full speed, and drops below the
ambient noise level in our lab somewhere between 7 and 9 volts. It does not
provide much airflow in comparison to other 120mm fans.

Once the fan was added to the test, the High-Riser’s performance improved tremendously.
The amount of airflow seemed to matter very little. The difference in performance
between full speed and 5V was a tiny 4°C. This means the High Riser
performs very well with only a minimum of airflow, and would probably
continue to perform well with even less airflow than our reference fan provides.


Our testing showed that the High-Riser is a very good performer, but how
good is it
? Our current champion is the Scythe Ninja. Can the High-Riser
beat it? The question just begs for a direct comparison…

Thankfully, the Ninja was tested with the same Nexus reference fan used for
the High-Riser, so a close comparison should be possible. The only variation
between the two test setups was the ambient temperature, which was a single
degree warmer when the Ninja was tested. In the table below, the Ninja’s temperatures have been dropped by one degree to compensate for the ambient temperature difference.

Thermalright HR-01 vs. Scythe
Ninja, both w/ Nexus 120mm fan
Fan Voltage
Thermalright HR-01
Scythe Ninja
Load Temp
°C Rise
Load Temp
°C Rise
not measured
not measured

With the fan at full speed, the Ninja wins hands down by a margin of 4°C.
However, as the fan speed is decreased, the performance advantage begins to
diminish, until it gets within a degree when the fan is below 7V. This is probably at the limit of our test resolution. As airflow
is reduced, the Ninja seems to decrease in performance more quickly than the High-Riser,
which suggests that the High-Riser might actually be a better heatsink with
low airflow, and thus do better in a passive setup. This is speculation. All that can be said for sure is that these are both very fine low airflow heatsinks! [Editor’s Note: The reality is that the noise reduction with the Nexus 120 fan as you go below ~8V is pretty much inaudible in just about any system, so there’s really no reason to run it that slow anyway. Of course, if you have a noisier fan…]


Thermalright has delivered a very competitive heatsink in the HR-01. Performance
is neck-and-neck with the Scythe Ninja, and that’s saying something. Yes, there
are nuances to the comparison between the two, but when it comes down to it,
the two perform very similarly. That means that Thermalright is back at the
top of the quiet high-performance heap — it seems they never fade for long.

We were pleased to report that installing the High-Riser was a breeze: It’s easier
to install than the Ninja, and a huge improvement over Thermalright’s own XP-120.
The High-Riser has one of the most elegant clips we’ve seen, similar to that used by Shuttle in some of their SFF systems.

Of course, there are always a few bones to pick, mostly related to compatibility.
At the moment, the only processors supported out of the box are AMD. Intel’s
current processors are not yet supported at all, as there are no mounting options
available for Socket 775. Older socket 478 processors require the purchase of
a separate clip. Still, the lack of Intel support isn’t as big a problem. Passive cooling is simply not an option for most of Intel’s
chips because they run so hot, and the performance (and silencing) markets are
currently dominated by AMD anyway.

There are some other potential issues:

  1. Not all motherboards
    have the CPU socket oriented in the same direction, so there may be a few situations
    where the heatsink cannot be mounted in the correct orientation. This hurts compatibility.
  2. The height
    of the heatsink may prove to be an issue in a smaller case.
  3. The cantilever effect is strong, so shipping with the HS on is not recommended.
  4. There is currently
    no standard way to attach a fan to the High-Riser, but cable ties or solid-core wire will both work well.

All of these are relatively minor issues, however. What counts most is performance, and
the High-Riser delivers. If you’re looking to build a high-end quiet system,
the only other serious contender among tower heatsinks is the Scythe Ninja.

* Excellent performance
* Potential for passive cooling
* Very easy installation
* Widely spaced fins make for good low-airflow performance
* Very well packaged
* Relatively light weight
* No fan clips available
* Not compatible with Socket 775
* Socket 478 support is only optional
* Restricted to a single orientation
* Very tall, cantilever effect

Much thanks to Thermalright
for the HR-01 sample.

* * *

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