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Asus EN8600GT OC GEAR graphics card

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Asus is one of the few manufacturers who doesn’t follow the mold with graphics cards. Not only do they produce both ATI and nVidia based cards, they seldom utilize the reference cooler; they even offer a wide variety of passively-cooled cards. The product we’re reviewing today isn’t passively-cooled, but it does have the potential to be quiet. The EN8600GT OC GEAR is a graphics card with a large, radial aluminum heatsink and an interesting feature we’ve never seen before: The “first hardware based real-time overclocking device for graphics cards overclocking and fan speed controller.”

October 30, 2007 by Lawrence

PCI-E Video Card
Market Price

When it comes to graphics cards, Asus is one of the few manufacturers who doesn’t
follow the mold. Not only do they produce both ATI and nVidia based cards, they
seldom utilize the reference cooler — in fact they even offer a wide variety
of passively-cooled cards. The product we’re reviewing today isn’t passively-cooled,
but it does have the potential to be quiet. The EN8600GT OC GEAR is a graphics
card with a large, radial aluminum heatsink and an interesting feature we’ve
never seen before: The “first hardware based real-time overclocking device
for graphics cards overclocking and fan speed controller.”

The model on the box seems to be an archer of some
kind. It’s fitting seeing as the box is large enough to hold an entire
quiver of arrows.


The box contents: Graphics card, OC Gear controller,
drivers and software, instructions and manuals, DVI adapter and component
out cable. In an act of seemingly random generosity, Asus also throws
in a CD wallet.


The OC Gear unit connects via internal USB header.


Asus EN8600GT OC GEAR/HTDP/256M: Specifications
(from the
product web page
Graphics Engine GeForce 8600GT
Video Memory 256MB DDR3
Engine Clock 540MHz
Memory Clock
1.4GHz (700MHz DDR3)
Memory Interface 128-bit
CRT Max Resolution 2048×1536
Bus Standard PCI Express X16
VGA Output YES, via DVI to VGA Adapter
HDTV Output (YPbPr) YES, via HDTV Out cable
TV Output YES, via S-Video to Composite
DVI Output DVI-I
Dual DVI Output YES
Adapter/Cable Bundled DVI to VGA adapter
HDTV-out cable
Software Bundled ASUS Utilities & Driver


The card is based on the nVidia Geforce 8600GT, which supports DirectX 10,
HDCP, as well as dual DVI output. It’s a popular choice for budget gaming and
high definition multimedia playback, though it lacks a HDMI port. The board
itself has a very clean layout with capacitors out of the way and plenty of
room around the heatsink. It’s a small card so it should have modest power and
cooling demands.

With fins spread out radially and the fan blowing down the center, the cooler
bears a striking resemblance to the old Thermaltake Crystal Orb and Zalman flower
heatsinks. The heatsink’s fins are tall – high enough to interfere with the
slot directly below the card, and are loosely spaced which is ideal for a low
airflow. The fan is larger than what you’d normally find on a video card —
a good sign as the larger the fan, the higher the airflow to noise ratio.


The OC Gear panel is a slick looking device with a very shiny surface and a
large control knob that’s easy to handle. After the panel is attached to an
internal USB header, it is mounted in a 5.25″ bay. It will not function,
however, until the OC Gear driver as well as Asus’ SmartDoctor utility are installed.
To display frames per second, Gamer OSD is also required. When we installed
the software bundle off of the provided disc, Gamer OSD refused to install,
claiming it was only supported by Windows Vista. Fortunately, the latest version
from the Asus website worked perfetly. It should be noted that SmartDoctor displays
much of the same information as the OCG unit, albeit with a less elegant presentation,
and it has a semi-customizable fan control feature.

GPU temperature displayed. There are sliders
for both core and memory frequency manipulation. A status message in the
upper left hand corner kindly lets us know that the video card is “OK.”


Fan RPM displayed.


The SmartCooling feature allows for automatic fan
throttling based on manually preset temperatures.

Once XP restarted, the OC Gear panel lit up like a Christmas tree. It’s a pleasing
blend of warm colors: yellow, orange, and red. The display shows graphical representations
of the current volume, GPU core frequency, GPU temperature, and video card fan
speed. It’s a fairly simple and intuitive device. The knob is pushed inward
to select the function you wish to adjust. Then you simply rotate the dial until
it reaches the desired level – a few turns clockwise and an another bar is illuminated.

Volume, GPU frequency, GPU temperature, and fan speed are displayed.
Additional bars light up as settings are increased.

Unfortunately there is no way of telling exactly what each function is set
to as the numerical display is only for displaying the frame-rate when a game
is running. The GPU core frequency is adjusted in only 5Mhz increments, so it’s
a fairly safe to overclock this way unless you get overzealous. nVidia’s nTune
utility confirmed that all changes made using the panel did in fact take. In
addition, changes in software settings, whether using nTune, SmartDoctor, or
ATI Tool, were also reflected in the panel display. You can use hardware, software,
or both to tweak the card: They do not conflict with one another.


Our old modified LX-6A19 (D8000) case from Cool Cases became our test
system housing.

Our first test procedure is an in-system test designed to determine the card’s
power consumption, and whether the card is capable of being adequately cooled
in a low-noise system. By adequately cooled, we mean cooled well
enough so that no misbehavior related to thermal overload is exhibited. Thermal
misbehavior in a graphics card can show up in a variety of ways, including…

  • 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

Test Platform

Measurement and Analysis Tools

System airflow is quite good, allowing the CPU and system fans to run at close
to inaudible speeds without compromising system cooling. The intake is about
the size of a 120mm fan. The only restriction is an air filter. A much more
restrictive cover for the filter was removed because it impeded the airflow
too much.

The one and only intake…


…and the same view, with the bezel removed.

There is only one point of exhaust: The Nexus 120mm case fan running at 7V.
Normally we test it at various voltages using a custom fan controller, but for
a budget video card with active cooling, it’s unlikely increasing the speed
of the exhaust fan would make much of a difference. We were more interested
in varying the speed of the video card’s fan to analyze its performance and
noise output. The 80mm fan in the Neo HE power supply was taken out of the picture
by using a custom-built duct to ensure that the fan never ramped up.

A fresh air duct isolates the power supply from the rest of the system.


Only one possible points of exhaust: The orange case fan.
The fan in the power supply draws its air from a duct that does not interact
with the rest of the system airflow.

The airflow in our test rig is typical of an ATX case. Air flows in through
the intake near the bottom of the front panel, and is pulled up to the top rear
corner. Most of this air will bypass the expansion cards altogether, but a small
amount will be pulled across the rear of the card as it is pulled towards the
CPU heatsink and the case fan. All of the air will exit the case via the exhaust

The air will flow from the lower right to the upper left, drawing a small
amount of air across the VGA card.

Thermal and power testing was conducted with the video card’s
fan at its lowest and default setting with the system in several different states:

1. Idle.
2. Running two instances of CPUBurn.
3. Running two instances of CPUBurn and ATI Tool’s artifact scanner to generate
as much heat and power draw as possible from both the CPU and GPU.

SpeedFan was used as our temperature measuring tool (the newest version supports
GPU temperature monitoring on some cards), and the test results were recorded
after the GPU temperature remained constant for approximately 10 minutes. In
the final, most demanding test with the video card’s fan running at its lowest
setting, ATI Tool was left running for 30 minutes and RTHDRIBL for 30 minutes
after that. Throughout this step we watched the screen for visual artifacts
that might indicate overheating. If either ATI Tool or RTHDRIBL detected artifacts
in this minimum airflow and maximum heat test situation, the card would be retested
for artifacts in previous applicable test states to identify additional points
of failure.

The card is determined to have passed our testing if it managed to survive
the duration of testing without ATI Tool or RTHDRIBL detecting any artifacts.

AC system power consumption was measured from the outlet using a Seasonic
Power Angel and actual DC power use was estimated/extrapolated using the efficiency
figures deduced from our Antec
Neo HE 430 review

During testing the ambient temperature was 21°C and the noise level was
approximately 18 dBA.



Since the card reviewed was not passively cooled, sound pressure level measurements
were made with the card inside the test platform case with the system powered
on and no other noise souces in the room. We wanted to know whether it would
increase the noise level of a relatively quiet system. Using the integrated
video on the motherboard, the system measured 21 dBA from 1m away using our
Bruel & Kjaer Sound Level Meter. It was just barely audible in our test
lab, with what little noise it produced coming mainly from the power supply

The EN8600GT’s fan speed was adjusted using SmartDoctor. At the fan’s lowest
setting (31% according to SmartDoctor), we recorded only a 1 dBA increase
over the baseline. While this was not that significant, the nature of sound
was more noticable — a low tonal hum rather than just the gentle smooth
sound of air circulating. At the fan’s default setting (75% according to SmartDoctor),
the sound level increased to 24 dBA, and the sound coming from the case was
distinct and easily identifiable as the main noise source. While quieter than
most video card fans, the sound quality became worse, and the tonal aspects
became more annoying. You’ll be able to hear this for yourself when you listen
to the recordings we made, further below. It really didn’t meet our high standards
so we decided not to test the card with the fan at its maximum speed. As it
turns out the fan was more than adequate for the task, even at minimal speed.


An initial testing phase was carried out using the integrated graphics on
the system motherboard to establish baseline levels for system power and CPU
temperature. Unfortunately, neither ATI Tool artifact scanner nor RTHDRIBL
would run on the integrated graphics chip. However, ATI Tool’s 3D View
did run and from past experience we know it generates a similar amount
of power consumption. We ran it in conjunction with CPUBurn to establish a
baseline for comparison.

VGA Test Bed: Baseline Results
(no external VGA card – 21 dBA@1m)
System State
CPU Temp
System Power
AC input
DC output (Est.)
CPUBurn x2
CPUBurn + ATITool


VGA Test Bed: Asus EN8600GT OC GEAR
System Load
Video Card Fan Speed*


System Power
AC input
DC output (Est.)
CPUBurn x2
CPUBurn +
ATI Tool
CPUBurn +
ATI Tool

*Minimum speed: 31% ; Default speed: 75%

While sitting idle and with CPUBurn running, the GPU temperature increased
by only 5-6°C with the fan set to the slowest setting. When CPUBurn and
ATI Tool were run in conjunction, the temperature shot up 22°C whether
the fan was spinning slow or at its default speed. This is a testiment to
either the low heat output of the GPU or the efficiency of the heatsink/fan.
Either way, it’s very obvious that cooling is not a problem. 70°C is very
modest for a graphics core and the fact that changing the fan speed didn’t
have any effect on the temperature when stressed was both surprising and impressive.

In addition, the EN8600GT passed our stability tests with flying colors.
No artifacts presented themselves during testing with either ATI Tool or RTHDRIBL.


A rough idea of the power consumption of the card can
be judged by comparing the total system power consumption with and without
the card installed. Our results were derived at by assuming:

1. The power consumption of the graphics card at idle
was equal to the difference in power demand between the two systems when both
were running CPUBurn.

2. The power consumption of the graphics card under
load was equal to the difference between the system with the card running
CPUBurn and ATI Tool simultaneously, and the baseline system running CPUBurn
only. This ensured that any load on the CPU from ATI Tool did not skew the
results, since the CPU was running at full load in both cases.

Video Card Power Consumption:
GPU State
Increase in System Power (AC)
Estimated Power Consumption

With an estimated power consumption under 40W, and active cooling, it was
no wonder the graphics card did not heat up much. Its power requirements are
fairly modest so we would’ve liked to see Asus use a quieter fan, or better
yet, a larger passive heatsink. Either could cool a 8600GT adequately with
minimal noise in a quiet, low airflow system.


Our second test procedure is designed to determine the card’s proficiency at
playing back high definition videos encoded with the popular H.264 and the up-and-coming
VC-1 codecs. We used the same test platform as our thermal and power test with
the Intel Pentium D 930 Presler processor. It’s a fairly low-end dual core CPU
by modern standards, so the difference in the amount of assistance it lent to
the GPU between the different test videos would be more easily distinguishable.

The clips were played with Windows Media Player 11 and a CPU usage graph was
created by the Windows Task Manger for analysis to determine the mean and average
CPU use. The higher the CPU usage, the lower the video card’s decoding ability.
If CPU usage reached extremely high levels and the video skipped or froze, we
concluded the video card failed to adequately decompress the clip. System power
consumption was also recorded.

Video Test Suite

BBC’s HD in Full Bloom is a 720p clip encoded
with H.264. It features time-lapsed photography, mainly of various flowers
blooming with vibrant colors and high contrast.
720p H.264: 1280×720 | 24fps | ~6200kbps


The Rush Hour 3 trailer is a 1080p clip encoded
with H.264. It has a good mixture of light and dark scenes, interspersed
with fast-motion action and cutaways.

1080p H.264: 1920×816 | 24fps | ~10100kbps


The Coral Reef Adventure trailer is a 1080p
clip encoded in VC-1 using the WMV3 codec (commonly recognized by the
moniker, “HD WMV”). It features multiple outdoor landscape and
dark underwater scenes.

WMV3 VC-1: 1440×1080 | 24fps | ~7700kbps


The Microsoft Flight Simulator X trailer is
a 720p clip encoded in VC-1. It’s a compilation of in-game action from
a third person point of view. While the source image quality is poor compared
to the other videos in our test suite, it was one of the few decent length
clips we could procure encoded using the Windows Media Video 9 Advanced
Profile aka WVC1 codec, a more demanding implementation of VC-1.

WVC1 VC-1: 1280×720 | 60fps | ~12200kbps


CPU Usage & Power Consumption
Video Clip
Mean CPU Usage
System Power
Consumption (AC)
Core 0
Core 1
720p H.264
1080p H.264

The EN8600GT blew through this section as well, with minimal CPU assistance
until our most demanding test clip. No freezing or stuttering was observed.
The 720p H264 and WMV3 clip barely used the second core at all. After some investigation
we found that this behavior, the favoring of one core over another during playback,
was evident in one of our Intel Core 2 Duo based systems as well, so it seems
to be a quirk with Intel dual core processors. On AMD 64 X2 systems, the load
on the cores seems more balanced while playing these clips.


These recording starts with 4~10 seconds of “silence”
to let you hear the ambient sound of the room, followed by 10 seconds of the
test system noise. The recording of the Asus video card has its fan at three
settings: Minimum, default, and maximum fan speeds. There’s a few seconds of
“silence” inserted between each 10 second stretch of noise to help
you remember the reference ambient.


recordings were made with a high resolution, studio quality, digital
recording system, then converted to LAME 128kbps encoded MP3s. We’ve
listened long and hard to ensure there is no audible degradation from
the original WAV files to these MP3s. They represent a quick snapshot
of what we heard during the review. Two recordings of each noise level
were made, one from a distance of one meter, and another
from one foot away.

one meter recording is intended to give you an idea of how the subject
of this review sound in actual use — one meter is a reasonable
typical distance between a computer or computer component and your ear.
The recording contains stretches of ambient noise that you can use to
judge the relative loudness of the subject. For best results, set
your volume control so that the ambient noise is just barely audible
Be aware that very quiet subjects may not be audible — if we couldn’t
hear it from one meter, chances are we couldn’t record it either!

one foot recording is designed to bring out the fine details of the
noise. Use this recording with caution! Although more detailed, it may
not represent how the subject sounds in actual use. It is best to listen
to this recording after you have listened to the one meter recording.

details about how we make these recordings can be found in our short
article: Audio Recording
Methods Revised


After all our testing, we have mixed feelings about the Asus EN8600GT

The actual graphics card itself is an exellent product, having
modest power requirement and impressive high definition playback ability in
a compact form. With an above-average cooler and low temperatures, there is
obviously a lot of headroom if you’re looking to squeeze better gaming performance
out of the card via overclocking. Gaming is an aspect we are not qualified to
discuss nor much interested in. Gaming performance analyses of the EN8600GT
OC GEAR can be found at a variety of other sites such as Legion
, HardwareZone
and AMDZone.

The fan is a little too noisy for our liking, though it performs
well. It’s obvious from our tests that a slower, quieter fan would’ve done just
fine. There’s also the matter of the extra expense added of the OC Gear unit.
It’s hard to justify the additional cost when for the same price, you can purchase
the next highest model, the 8600GTS. It’s not a particularly useful piece of
hardware, as much of its functionality can be reproduced with various software
programs. Fan speed control can be customized and overclocking done on the fly
from the desktop with very little interaction by the user, and frame-rate can
be displayed on-screen in almost all modern games. It’d be a lot more useful
if all the information was displayed numerically, or if you could set dynamic
fan/overclocking settings using the panel. Reaching for the dial and adjusting
each setting is tedious and not knowing exactly how high or low you’re adjusting
them is unsettling.

We applaud the innovation shown by Asus, but it’s clear that improvements
can definitely be made to the OC Gear module to make it more functional and
worthwhile. It would also be advisable to bundle it with a high-end card instead,
as the price difference wouldn’t be as glaring and perspective buyers would
be more willing to spend a bit more.

Many thanks to ASUSTeK
for the sample of the EN8600GT OC GEAR/HTDP/256M

* * *

SPCR Articles of Related Interest:
Sytrin KuFormula VF1 Plus
graphics card cooler

Fanless PCIe
Graphics Cards from Asus and Aopen

Gigabyte GV-N66256DP Fanless AGP video card
VGA Cooler Roundup: A
Thermalright, two Zalmans, and an Arctic Cooling

* * *

this article in the SPCR Forums.

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