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Asus EN9400GT Silent Edition

The Asus EN9400GT Silent edition is a passively cooled PCI-E graphics card based on nVidia’s GeForce 9400 processor. If GeForce 9 was an office hierarchy, the 9400 would be its star mail boy. To differentiate itself from the other mail boys, it only has to be silent and power efficient.

Mar. 14, 2009 by Lawrence Lee

Asus EN9400GT SILENT/DI/512MD2
PCI-E Graphics Card
Street Price

Modern integrated graphics platforms have evolved to the point where they
possess all of the features of their low-end discrete counterparts with poorer
3D performance being their only failing. However, any informed user seeking
good 3D performance for gaming would not consider either option, so that
advantage of the budget discrete video card is all but negligible. Budget graphics cards still have some value however, for example, as a cheap upgrade for older systems incapable of decoding
HD video or to support additional displays in a multi-monitor environment. There
are also enthusiasts with no interest in gaming, who build PCs using ATX motherboards
without integrated video. Even if they don’t play games, they still need graphics.

For such scenarios, even a bottom of the rung GPU would be acceptable. One candidate is the Asus EN9400GT Silent, a passively cooled card based on nVidia’s GeForce 9400 processor. If GeForce 9 was an office hierarchy, the 9400 would be its star mail-boy. To differentiate itself, it really
only has to be silent (taken care of already) and power efficient.

Our Asus EN9400GT Silent sample.

At first glance the card has a relatively large heatsink (compared to the size
of the PCB) with a good basic design — plenty of surface area for heat
dissipation. We should note at this point that although the card’s specifications
list a HDMI port, the sample we received had a standard TV-out port instead.
We suspect that it was simply an early review sample, and that the retail version
does have a HDMI port included on the backpane

Asus EN9400GT SILENT/DI/512MD2: Specifications
(from the
product web page


Technical specifications according to GPU-Z.

Our sample was manufactured using a 65nm process, based on nVidia’s G96 core.
As an entry level card it has only 16 stream processors, a 128-bit memory interface
and relatively slow (400MHz) GDDR2 memory.


The EN9400GT Silent has a large passive heatsink spanning the entire length
of the card. It arcs outward from the center to avoid board components.
The back panel has a vanity grill stamped into it — it is not a serious
point of ventilation.


The heatsink has thick, broad fins on both sides of the arches. The fins
measured approximately 0.90 mm thick on average and were spaced 4 mm apart.
The wide spacing is ideal for passive operation.


The PCB measures 16.7 cm long, but the cooler overhangs the edge resulting
in an overall length of 17.0 cm.


From the side we can see plenty of clearance for the various capacitors
and other components residing on the surface of the circuit board. The
card is equipped with bare 2.5ns GDDR2 memory chips (400MHz).


Warning — removing the heatsink from a card generally voids the product’s
warranty. Do so at your own risk. Note that all testing on the card was performed
before the cooler was removed.

The heatsink is secured to the card by four spring-loaded screws. The
mounting holes form a 53.5 mm square around the GPU core.


The GPU core is mated to the heatsink base using a thin layer of hard
thermal compound. Some force was required to break the seal.


The area around the core lacks a shim, so four nuts are affixed around
the base of the heatsink to maintain proper spacing. The cooler accounts
for 250 grams of the card’s total mass of 400 grams.


The card installed in our test system.


Our test procedure is an in-system test, designed to:

1. Determine whether the card’s 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 ways, including:

  • Sudden system shutdown, bluescreen 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 life span of the graphics card, and sometimes to
the system OS.

2. Estimate the card’s power consumption. This is a good indicator of how efficient
the card is and will have an effect on how hot the stock cooler becomes due
to power lost in the form of heat. The lower the better.

3. Determine the card’s ability to play back high definition video, to see
if whether it is a suitable choice for a home theater PC.

Test Platform

Measurement and Analysis Tools

Testing Procedures

Our first test involves recording the system power consumption using a Seasonic
Power Angel as well as CPU and GPU temperatures using SpeedFan and GPU-Z during
different states: Idle, under load with CPUBurn running to stress the processor,
and with CPUBurn and ATITool’s artifact scanner (or FurMark — whichever produces
higher power consumption) running to stress both the CPU and GPU simultaneously.
This last state mimics the stress on the CPU and GPU produced by a modern video
game. The software is left running until the GPU temperature remains stable
for at least 10 minutes. If artifacts are detected by ATITool or any other instability
is noted, the heatsink is deemed inadequate to cool the video card in our test

If the heatsink has a fan, the load state tests are repeated at various fan
speeds while the system case fan is left at its lowest setting of 7V. If the
card utilizes a passive cooler, the system fan is varied instead to study the
effect of system airflow on the heatsink’s performance. System noise measurements
are made at each fan speed.

Video Playback Testing

For our second test, we play a variety of video clips with PowerDVD. A CPU
usage graph is created via the Windows Task Manger for analysis to determine
the approximate mean and peak CPU usage. If the card (in conjunction with the
processor) is unable to properly decompress the clip, the video will skip or
freeze, often with instances of extremely high CPU usage as the system struggles
to play it back. High CPU usage is undesirable as it increases power consumption,
and leaves fewer resources for background tasks and other applications that
happen to be running during playback. Power draw is also recorded during playback.

Video Test Suite

1080p | 24fps | ~10mbps
Rush Hour 3 Trailer 1
is a H.264 encoded clip inside an Apple
Quicktime container.


1080p | 24fps | ~8mbps
Coral Reef Adventure Trailer
is encoded in VC-1 using the WMV3
codec commonly recognized by the “WMV-HD” moniker.


1080p | 24fps | ~19mbps
VC-1: Drag Race is a recording of a scene from
network television re-encoded with TMPGEnc using the WVC1 codec, a more
demanding VC-1 codec.


Estimating DC Power

The following power efficiency figures were obtained for the
Seasonic S12-600
used in our test system:

Seasonic S12-500 / 600 TEST RESULTS
DC Output (W)
AC Input (W)

This data is enough to give us a very good estimate of DC demand in our
test system. We extrapolate the DC power output from the measured AC power
input based on this data. We won’t go through the math; it’s easy enough
to figure out for yourself if you really want to.


BASELINE, with Integrated Graphics: First, here are the results of
our baseline results of the system with just its integrated graphics, without
a discrete video card. We’ll also need the power consumption reading during
CPUBurn to estimate the actual power draw of discrete card later.

VGA Test Bed: Baseline Results
(no discrete graphics card installed)
System Power
DC (Est.)
Ambient temperature: 21°C
Ambient noise level: 11 dBA
System noise level: 12 dBA


VGA Test Bed: Asus EN9400GT SILENT
Sys. Fan Speed
System Power
DC (Est.)
12 dBA
CPUBurn + FurMark
CPUBurn + FurMark
15 dBA
CPUBurn + FurMark
18 dBA
Ambient temperature: 21°C.

The thermals of the EN9400GT Silent were very low during testing, staying
below 70°C even when airflow was strictly limited. Increasing the speed
of the only system fan to 9V did not improve the GPU temperature,and pumping
it up to 12V resulted in only a 4°C difference. The card’s fairly low power
consumption and the heatsink’s simple yet efficient design compliment each other
well. It is an excellent combination for a silent PC.


The power consumption of an add-on video card can be estimated by comparing
the total system power draw with and without the card installed. Our results
were derived thus:

1. Power consumption of the graphics card at idle – When CPUBurn is
run on a system, the video card is not stressed at all, and stays in idle mode.
This is true whether the video card is integrated or an add-on PCIe 16X device.
Hence, when the power consumption of the base system under CPUBurn is subtracted
from the power consumption of the same test with the graphics card installed,
we obtain the increase in idle power of the add-on card over the
integrated graphics chip (Intel GMA950). (The actual idle power
of the add-on card cannot be derived, because the integrated graphics does draw
some power — we’d guess no more than a watt or two.)

2. Power consumption of the graphics card under load – The power draw
of the system is measured with the add-on video card, with CPUBurn and FurMark
running simultaneously. Then the power of the baseline system (with integrated
graphics) running just CPUBurn is subtracted. The difference is the load power
of the add-on card. (If you want to nitpick, the 1~2W power of the integrated
graphics at idle should be added to this number.) Any load on the CPU from FurMark
should not skew the results, since the CPU was running at full load in both

Both results are scaled by the efficiency of the power supply (tested
) to obtain a final estimate of the DC power consumption.

Power Consumption Comparison (DC)
Est. Power (Idle)
Est. Power (Load)
Asus EN9400GT Silent
PowerColor SCS3
HD 4650
Asus EAH3650 Silent

Our EN9400GT Silent sample exhibited very low power consumption, beating out
both the PowerColor HD 4650 and Asus HD 3650. Idle power consumption, we feel,
is still not low enough. A modern integrated graphics chip uses about the same
amount of power on full load as the EN9400GT when idle.


Extracting the card’s BIOS using GPU-Z, we examined the contents using the
BIOS Editor
. It gives insight into how the card behaves in regard to clock
rates, voltages and fan speeds (the latter not applicable in this case).

BIOS Clockrates.

The BIOS indicates that it runs in an underclocked state during 2D operation,
but during testing the clock speeds remained at 550 / 400 MHz at all times according
to GPU-Z.

BIOS Voltages.

The BIOS also indicates a 0.1V undervolt in 2D mode.

Video Playback

As a low-end card, the EN9400GT is ideal for non-3D use, i.e. anything but
gaming. Decoding popular high definition video formats is really all a good
budget graphics card is good for in most cases. The better the hardware acceleration,
the less strain is placed on the CPU, freeing it up for other tasks.

Video Playback Comparison
Video Clip
Asus EN9400GT Silent
PowerColor SCS3
HD 4650
Asus EAH3650 Silent
Mean CPU
Rush Hour
Coral Reef
Drag Race

The EN9400GT does a fairly good job with VC-1 encoded content, using about
6W less than the HD 4650/3650 during the Coral Reef clip and matching the HD
4650 during the Drag Race clip. CPU usage was similar between the three cards
during VC-1 playback. Unfortunately, the card dropped the ball during the H.265
Rush Hour clip which is typically the least demanding video in our test suite.
Rendering this clip is usually trivial for modern GPUs, but the EN9400GT required
more than 40% CPU utilization to play it and expended 10W more doing so than
the two comparison cards.


These recordings were made with a high
resolution, lab quality, digital recording system
inside SPCR’s
own 11 dBA ambient anechoic chamber
, 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.

These recordings are intended to give you an idea of how the product sounds
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. 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!

The recording starts with 5~10 seconds of room ambiance, followed by 5~10 seconds
of the VGA test system without a video card installed, and then the actual product’s
noise at various levels. As this particular card did not add any noise the test
system, we have provided only a recording of the test system with its system
fan set to the levels tested. For the most realistic results, set the
volume so that the starting ambient level is just barely audible, then don’t
change the volume setting again.


Gaming: Please check out the gaming-oriented reviews of the 9400 GT
at Bjorn3D,
and XSReviews,
and techPowerUp. The general consensus is that the 9400 GT is a slow GPU, unsuitable for playing the majority of today’s 3D PC gaming titles, though a few may be bearable if you don’t mind low resolution and detail levels.

Video Playback: VC-1 playback was good; very power efficient for a discrete
card. Unfortunately, for whatever reason, H.264 playback was more stressful
on the system than is usual with most GPUs. We hope it was simply a software
or driver bug, though it should be noted that the test system was still good
enough to render H.264 smoothly, despite it being somewhat antiquated. This
shouldn’t be an issue unless you have a very slow CPU.

Cooling: As the 9400 GT uses very little power, it was not necessary
to incorporate heatpipes or a fan in the heatsink design. Previous Asus passive
cooler featured fins pointing every which way and attempts to direct air along
guides and other eccentricities. This time around, Asus did not over-think design
and went with something basic which was quite effective. GPU temperatures were excellent,
even in a test system with very low airflow.

Power Consumption: By our estimates, the EN9400GT Silent requires approximately
11W when idle and up to 23W DC when stressed to the limit. The load figure is
the lowest we’ve measured on a discrete graphics card, though it probably
won’t be reached for most users. 11W at idle is also fairly low, but it is
still a long way from the efficiency of an integrated graphics chip.

Overall the EN9400GT Silent is a decent budget graphics card.
It will result in no additional noise, little if any thermal impact, and a small increase in power consumption. We are unsure what this model will go for but other Asus variants of the 9400 GT are currently retailing for around $60. There are several affordable fanless budget graphics cards $40-$50 range, and those willing to pay a little more can get a lot more 3D performance by choosing an ATI HD 4650 / 4670, or even an nVidia 9500 GT.

Asus EN9400GT SILENT/DI/512MD2

* Completely silent and fairly cool
* Low power consumption
* Small size


* Severely lacking in 3D performance
* Possibly too expensive

Our thanks to ASUSTeK
for the video card sample.

* * *

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EN9800GT Matrix Edition

the Gap: ATI Radeon HD 4830

Redefining Budget Gaming Graphics: ATI’s
HD 4670

Asus ENGTX260: A Quiet Graphics
Card for Gamers?

Diamond Radeon HD4850

* * *

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