Arctic Cooling’s Accelero S1 fanless GPU coolers promises excellent cooling with its huge size and open fin spacing. We put it through its paces in our new VGA testing platform.
December 26, 2007 by Lawrence
|Arctic Cooling Accelero S1 |
Passive VGA Cooler
Arctic Cooling is a Swiss company dedicated to quiet CPU and GPU cooling. Back in the day, their VGA Silencer heatsinks were on top of the silent computing world, with Zalman’s passive heatpipe GPU coolers being their only real competition.
Arctic Cooling is now receiving accolades for their own fanless GPU coolers,
the Accelero S1 and S2.
The S1 doesn’t
have a fancy design. There are is no complicated array of swirling heatpipes
or a funky fan design, just a bunch of heatpipes and aluminum fins. So
how does it expect to be a good performer? By being big. Measuring approximately
22cm x 14cm, it’s the widest and longest graphics card cooler we’ve had
in our lab. With a measly $20 price-tag, it’s also the cheapest.
Accelero S1: Main Features (from the
product web page)
Features & Brief
|We hope |
so. Arctic Cooling also sells a Turbo Module with two fans for the S1/S2
if you find its performance to be inadequate.
4 Heat Pipes
|Same as the Zalman |
VF1000, though much longer.
Special Heat Spreader for Voltage Regulator Cooling
|Extra heatsinks provided |
for certain models of ATI X1800 and X1900 series.
|8 ramsinks included.|
|High Reliability||Difficult to verify.|
|Low Weight||Surprisingly light |
for a heatsink of its size.
|6 Years Warranty||Six is such an odd number — must be a European thing.|
Accelero S1: Technical Data (from the
product web page)
|Heatsink Dimensions||140(L) x 215(W) x 32(H) |
|Heat Pipe Dimensions||6 mm x 4|
|Accessories||2 Voltage Regulator Heat |
8 Memory Heat Sinks
|Compatibility||ATI: HD 3870, 3850, X1950, |
X1900, X1800 series
nVIDIA: GeForce 8800GTS(G92), 8800GT, 7950, 7900, 7800, 6800 series
There’s no ignoring the size of the S1 — it’s much larger than the card(s) it was designed to cool. Pictures just don’t
do it justice — when you actually have it in your hand and realize
you can’t wrap your fingers the entire width, you’ll be in awe. But is the
S1 too big? The height won’t be an issue for most as it only obstructs one
extra expansion slot. Lengthwise, the S1 measures 21.5cm (~8.5"), but
it doesn’t extend all the way the edge of the PCI covers — it sits
about 1cm away. In effect it’s about the same length as most modern high-end
video cards. That leaves only the width, which extends past the edge of
the video card by approximately 4cm. In my Antec Solo, the S1 is only a
few millimeters longer than my Scythe Ninja and I reckon any case with a
120mm fan in the back will be wide enough to accomodate the S1. The area
beteween the edge of the expansion cards and the side panel in most tower
cases typically goes wasted so its only logical to take advantage of this
As with most heatsinks you see today it is comprised of a copper base,
copper heatpipes, and aluminum fins. The fins are friction-fit, with ample
gaps of approximately 3.5mm — perfect for passive cooling in a low
airflow environment. It weighs in at only 290 grams because most of the
S1’s area is just air. Attached to the final fins at each end are plastic
covers which appear to be a flimsy way of binding the whole thing together.
Despite this, the fins are quite secure and difficult to bend, especially
where they contact the heatpipes.
Arctic Cooling pre-applies their MX-1 thermal compound to the base of
all their heatsinks — it’s a fairly good product according to various
reviews around the web. We immediately cleaned it off however as it’s important
we use the same thermal interface material in all of our heatsink tests.
It was also necessary to take a look at the base, which turned out to be
very flat but not polished at all — machine marks were clearly visible.
The ends of the heatpipes appeared to be well soldered to the base as there
were no visible gaps as far as I could tell.
Unlike Zalman’s VGA heatsinks, there are only one set of mounting holes,
which limits compatibility. If you own an incompatible card, there are alternatives:
The Accelero S2, which has half the number of heatpipes and is slightly
narrower, and the recently announced Accelero S1 Rev. 2, which is identical
to the S1 only with a revised mounting scheme. Most of today’s medium to
high-end video cards are in the compatibility list with the notable exceptions
of ATI’s HD 2xxx series and the Geforce 8800GTS/GTX/Ultra.
The first step in installing the Accelero S1 on our Radeon X1950XTX test
card was to attach the ramsinks. This unfortunately proved problematic as
the 3M thermal adhesive was incredibly weak. Each
memory chip was painstakingly cleaned eto make sure the surface was immaculate, and pushed down firmly
on each ramsink for a good minute. Upon flipping the card upside down however,
several of them decided they no longer belonged on the card and fell off
like lemmings into the sea. Perhaps application with longer, more persistant
pressure, or possibly heating them up beforehand would have made them adhere
better, but who has the time or the patience!? Bottom-line: They
should work right out of the box but they don’t. Zalman low profile ramsinks were used instead — these have never fallen off despite being re-used numerous
times in the past.
Thermal compound was applied to the GPU core, and the card was flipped
upside down to be placed onto the heatsink. The S1 is mounted with four
fine-threaded screws with thin washers placed in between them and the back
of the card. Arctic Cooling’s instructions dictate that the two screws nearest
the gold contacts of the card should be partially installed, then the opposite
end of the card be lifted up to install two L-shaped plastic clips.
The top side of the "L" clip grasps the edge of the card while
a limb on the bottom side is inserted through the fins. On the other side,
T-shaped clips go in between the same fins and latch on. These clips act
as spacers, maintaining a set distance between the card and the fins of
the heatsink. This prevents the heatsink bending downward (say if you decide
to attach a fan to it) and also keeps board components away from the fins.
The fins may interfere if your card has tall capacitors, but luckily such
components are absent on our X1950XTX. The spacers should be placed between
the 1st/2nd and 3rd/4th heatpipe, but they might need to be adjusted if
anything gets in the way. Also note that these clips are somewhat difficult
to remove, so think twice before you place them. If you do not plan on adding
a fan, you can probably omit this step altogether.
Full details of our latest VGA test system is detailed in a recent article. Our test procedure is an in-system test to determine whether the
cooler is adequate for use in a low-noise system. By adequately cooled,
we mean cooled well enough that no misbehavior related to thermal overload is
exhibited. Thermal misbehavior in a graphics card can show up in a variety of
- Sudden system shutdown or reboot without warning.
- Jaggies and other visual artifacts on the screen.
- Motion slowing and/or screen freezing.
Any of these misbehaviors are annoying at best and dangerous at worst —
dangerous to the health and lifespan of the graphics card, and sometimes to
the system OS.
Pentium D 930 Presler core processor. Official TDP of 95W.
i945Ga-PHS motherboard – Intel i945Ga Chipset; built-in VGA.
G-Power 2 Pro heatsink, modified with a Scythe
Slip Stream 500RPM 120mm fan.
DDR2 RAM, PC2-6400, 1024 MB
- Samsung MP0402H 40GB
2.5" notebook hard drive, floating in a DIY clothing elastic suspension
in bottom HDD bay.
S12-600 ATX12V v2.0 compliant power supply, modified with a
Slip Stream 800RPM 120mm fan @ 5V.
P180B case, modified in detail below.
- Nexus 120mm
fan connected to a variable fan speed controller.
The Antec P180 case has two front 120mm intakes — the bottom one feeds
fresh air to the hard drive and power supply section while the top one allows
airflow into the rest of the system. The stock filter and door over the intake
vent for the main chamber are removed — replaced with the metal mesh for
the top panel 120mm fan. The filter for the lower PSU/HDD chamber is retained,
but its cover door is also removed to reduce airflow impedance. The front door
is cast away as well to improve airflow. The top three optical drive bays are
covered with a block of open-cell foam which allows some air to flow in but
also absorbs much of the internal sound from coming out.
The processor is cooled by a modified Gigabyte G-Power 2 Pro without its plastic
shroud utilizing a Scythe Slip Stream 120mm 500RPM fan, connected directly to
the motherboard’s CPU fan header — it is completely inaudible. Above it,
a block of foam is positioned on the ceiling over top fan vent, which also draws
some air in when the system is running.
The only system fan is a Nexus 120mm mounted in the rear exhaust position with
silicon rubber nubs made expressly to reduce vibration conduction into the case.
It is powered by the PSU through to a customized fan speed controller using
zener diodes. A knob protruding from the wall of foam at the front allows the
fan voltage to be easily varied.
The power supply is a Seasonic S12-600 with the stock fan replaced by a Scythe
Slip Stream 120mm 800RPM fan, hard-wired to run at 5V. The fan just barely starts
up, and spins extremely slowly, at ~400RPM. Air expelled from the PSU is only
mildly warm, even during long sessions of high power testing.
The notebook hard drive is suspended in the lower drive bay with zip ties and
cloth elastic with a 2mm round cross-section. No vibration from the drive can
be felt on the drive bay. Foam is attached to both sides of the compartment
divider as an extra silencing measure.
The overall noise level of the system is excellent at only ~19 dBA@1m with
the system fan @ 7V. For comparison, during the quietest moments in our lab
with all the computers turned off, the ambient noise level is around 17 dBA.
Measurement and Analysis Tools
- ATI Tool
as a tool for stressing the GPU and to show GPU temperature
P6 processor stress software.
version 4.33 to show CPU temperature
Power Angel AC power meter, used to monitor the power consumption
of the system
- A custom-built internal variable fan speed controller to power the
- A custom-built external variable fan speed controller to power the
VGA heatsink fan (if applicable)
- Bruel & Kjaer (B&K) model 2203 Sound Level Meter, used to
accurately measure SPL (sound pressure level) down to 20 dBA and below.
Heatsinks are installed on an ATI Radeon X1950XTX (if compatible) — a high-powered
video card that features a thermal sensor built into the GPU core. The accuracy
of the sensor is unknown. The video memory heatsink is usually left on unless
it interferes with the VGA cooler.
Our main test consists of ATI Tool’s artifact scanner running in conjunction
with CPUBurn to stress both the graphics card and processor simultaneously.
It is a realistic test that mimics the stress on the CPU and GPU produced by
a modern video game, only more consistently. The software is left running until
the GPU temperature stabilizes for at least 10 minutes at which point, both
the CPU and GPU temperatures are recorded. In addition we also take measurements
of the system’s overall noise level and power consumption using a B&K Sound
Meter and a Seasonic Power Angel respectively. If the heatsink has a fan, the
procedure is repeated at various fan speeds while the system fan is left at
the lowest setting of 7V. If it is a passive cooler, the system fan instead
is varied to study the effect of system airflow on the heatsink’s performance.
If artifacts are detected in ATI Tool or other instability is noted, the heatsink
is deemed inadequate to cool the video card in our test system. Usually artifacts
begin to appear when the GPU temperature reaches between 90°C and 95°C.
Preliminary testing is also done at idle, and with only CPUBurn running for
comparison. For idle results, the system is left stagnant for 10 minutes before
ATI Tool is loaded and the first temperature it reports is used. We do this because
on our test platform, after ATI Tool is loaded, it puts some kind of stress on
the GPU, causing the temperature to climb immediately (even if it is left idle
for hours beforehand) and the power consumption to increase by approximately
10W. We theorize that initially the card is in 2D mode, either underclocked
or undervolted (or possibly both) and that ATI Tool automatically puts it in
3D mode, which would account for the rise in temperature and power draw. ATI Tool
is left running in the background for the remainder of testing which is why
the GPU temperature during CPUBurn will appear higher compared to idle. Consider
this the difference between 2D idle and 3D idle.
PASSIVE COOLING TEST RESULTS
First the S1 was tested passively as it was meant to be, with only a
single system fan running. Ambient conditions during testing were 22°C and
20 dBA. It was slightly louder than normal in our lab that day, mainly because
of the rainy weather.
Results: Accelero S1, Passive
System Fan Speed
CPUBurn + ATI Tool
* ATI Tool detected delta artifacts, heatsink failure
With the system fan at 7V and 9V, the ATI X1950XTX GPU temperature leveled off at 95°C.
In addition, artifacting was detected in ATI Tool meaning the S1 wasn’t able
to cool the video card properly in the test platform. A few degrees lower
and it would have made it, but it wasn’t quite up to snuff. When the system fan speed was increased to 12V however, the temperature dropped dramatically
and stability was achieved. A sound pressure level of 23 dBA@1m is pretty quiet but not silent, however.
Another Nexus 120mm fan was then installed as a front intake, attached
to the same fan controller to see what difference it would make.
Comparison: Accelero S1 (Passive), One vs. Two
System Fan Speed(s) SPL@1m GPU Temp. VGA Amb. CPU Temp. System Power 7V <20 dBA 95°C* 68°C 43°C 270W 9V 21 dBA 271W 7V/7V 22 dBA 90°C* 69°C 275W 12V 23 dBA
60°C 38°C 267W 9V/9V 25 dBA 89°C 68°C 42°C 276W * ATI Tool detected delta artifacts, heatsink failure
With both fans at 7V, the SPL was 22 dBA@1m and the temperature
decreased to 90°C — but still not enough for ATI Tool to stay artifact-free.
9V did do the trick, with a miniscule one degree improvement, but at 25 dBA,
it was louder than the single system fan at 12V. In our test platform it appears
that exhaust airflow is the main factor in passive VGA heatsink performance.
Comparison: Zalman VF900-CU vs. Arctic Cooling
Accelero S1 (Passive)
Zalman VF900-CU Arctic Cooling Accelero S1 Fan Speed System Noise GPU Temp. VGA Amb. System Fan Speed(s) System Noise GPU Temp. VGA Amb. 5V 20 dBA 94°C* 61°C 7V <20 dBA 95°C* 68°C 7V 22 dBA 93°C 60°C 7V/7V 22 dBA 90°C* 69°C 9V 24 dBA 92°C 58°C 12V 23 dBA
60°C 12V 28 dBA 89°C 56°C * ATI Tool detected delta artifacts, heatsink failure
Note: Ambient temperature during VF900 testing was 1°C lower.
Compared to the Zalman VF900-CU, the Accelero S1 in passive mode is very impressive. With
just the system fan @ 7V, it matches the cooling performance of the VF900
@ 5V. With the system fan @ 12V, the noise level was equivalent
to the VF900 @ approximately 8V, but the S1 outperformed it easily despite
not having any direct airflow pushing through its fins. The quality of noise
from the system fan, however, was much smoother and more benign than that of the VF900. Neither heatsink
was ideal for the X1950XTX, however. The S1 needs a fan to handle the heat of the X1950XTX.
ACTIVE COOLING TEST RESULTS
We had not yet received the Turbo Module from Arctic Cooling, but we did
have a variety of 80mm, 92mm and 120mm fans to choose from. We
went straight for a Nexus 120mm as there was no compelling reason to try a smaller
fan. Users savvy enough to add their own quiet fan would surely
choose a 120mm as well. Some thick double-sided tape was applied to the corners
to keep the fan from being in direct contact with the fins and to accomodate
the plastic spacers. Each corner was strapped tightly to the S1 with zip-ties.
A Nexus 120mm fan strapped to the S1.
A marriage of silent cooling prowess.
Comparison: Zalman VF1000 LED vs. Accelero S1 + Nexus
Zalman VF1000 LED Fan Speed Accelero S1 (Nexus 120mm) System Noise GPU Temp. VGA Amb. System Noise GPU Temp. VGA Amb. 20 dBA 76°C 56°C 5V <20 dBA 67°C 57°C 22 dBA 74°C 55°C 7V 21 dBA 64°C 54°C 24 dBA 72°C 54°C 9V 22 dBA 53°C 29 dBA 70°C 53°C 12V 23 dBA 63°C 52°C Note: Ambient temperature during VF1000 testing
was 1°C lower.
Compared to our previous champion, the Zalman VF1000, the S1 with Nexus 120mm
fan was clearly superior. At each fan speed level, the noise output
was lower and more pleasing to the ear. The temperature results were impressive
to say the least. With its fan at full blast, the VF1000 could not match
the performance of the S1 and Nexus 120 fan even at an inaudible 5V. Only a marginal amount
of direct airflow was needed to push the S1 straight past competency and into
first-class status — increasing the fan speed past 7V was pointless as
there was no significant improvement.
The Accelero S1 was not able to cool our X1950XTX passively without some
extra system airflow, but it came very close — that’s an
achievement in itself, given how hot this VGA card runs. Is passive performance, surprisingly, was about equal to that of the active Zalman VF900-CU.
Current generation cards are
more power efficient than the ATI X1950XTX, so the S1 should
perform even better with a Radeon HD 3850/3870 or Geforce 8800GT/GTS(G92),
which have been identified by Arctic Cooling to be suitable for the
S1 to cool fanlessly. (According to the power consumption figures derived by competent hardware review sites,
all of those cards are less demanding than the ATI X1950XTX.)
With a Nexus 120mm fan attached, the S1 became the best graphics card heatsink
we’ve ever tested. The wide fin spacing made adding a fan easy and only a
small amount of airflow was required to make it a top notch cooler. We hypothesize
that a low speed 80mm or 92mm fan would also perform well. If you cannot afford
to forfeit two extra expansion slots to add a fan, Arctic Cooling’s Turbo
Module may be a good choice — it’s a twin 80mm fan add-on which is thinner
enough to only occupy one extra slot. They also sell a flexible bridge connector
for those wishing to use the S1 (or a pair of S1’s) in an SLI configuration.
The heatsink’s proportions shouldn’t deter many users, but if you
own a slim case, it’s out of the question. Most of the extra real estate (compared to its competitors) is
not usually taken advantage of anyway. It may be prudent however to check
your motherboard for components directly below the space the S1 would occupy
— it may put SATA ports for instance, out of reach.
It does have a couple of drawbacks, the first being the woefully inadequate
memory heatsink adhesive. Sure it’s not much trouble to use a little super glue or thermal
adhesive to mount them, but we shouldn’t have to. The second problem is compatibility:
The S1 only has one set of mounting holes which may drive users
with incompatible cards to the similarly-priced, but inferior Accelero S2.
Fortunately, Arctic Cooling has addressed this problem by releasing a new
revision of the S1.
It’s hard not to recommend the Arctic Cooling Accelero
S1 to just about everybody. Unless your graphics card is incompatible or your
case isn’t wide enough to acommodate its size, the S1 should be your first
choice for quietly cooling a hot GPU. It’s a great performer, both passive and actively-cooled, and an unbeatable
value at the $20 street price. It’s cheap, proficient, and
hard to resist.
Pros * Good passive performance
* Fantastic performance with a fan
* Easy to install
* Only takes up one extra slot
* Incredibly affordable
Cons * Poor ramsink adhesive
* Limited compatibility
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