PowerColor SCS HD4650: A Fanless Budget Graphics Card

Table of Contents

The Radeon HD 4650 is a slightly cut-down version of the HD 4670, but still retains much of the performance of its bigger brother. The SCS is PowerColor’s fanless version of the HD 4650, featuring a simple heatpipe cooler reminiscent of the Arctic Cooling Accelero series. Does it perform well, or is it simply adequate?

Feb 6, 2008 by Lawrence Lee

PowerColor SCS3 HD4650
AX4650 512MD2-S3
PCI-E Graphics Card
Street Price

The ATI Radeon HD 4670 we reviewed
late last year was a modest but efficient graphics that delivered better than
expected 3D performance while drawing only 40W at maximum load. Unfortunately,
it was saddled with a small, whiney fan. It is a shame that, despite their modest
power consumption, budget cards are so often equipped with noisy coolers that
sound no better than those found on high performance cards.

The PowerColor SCS3 HD4650 is an exception, featuring a completely fanless
heatsink. Its HD 4650 GPU uses the same RV730 core as the HD 4670, but with
a reduced clock speed and slower memory. As a cut-down version, the power draw
should be even lower, making it a prime candidate for passive cooling.

The PowerColor SCS3 HD4650.


Technical specifications according to GPU-Z.

The HD 4650 is a 55nm GPU with the same 320 unified shaders as the HD 4670.
It has a lower core clock speed of 600Mhz, with memory running at 400MHz. It
utilizes slower DDR2 memory chips (most 4670’s have GDDR3/DDR3 memory), but
they are rated for 2.0 ns, which should be good up to 500MHz.

PowerColor SCS3 HD4650: Specifications
(from the
product web page

Our sample came as a bare card without a box or accessories. According to the
, the retail version ships with a DVI to VGA adapter and component-out
cable. The HDMI adapter is listed as “optional” so it does not appear
to be included. The card does output HDMI audio if the proper adapter is utilized.


The card’s main attraction is the passive cooler, which increases the height
of the card enough that it occupies one extra slot below it. It bears a vague
resemblance to the Arctic Cooling
Accelero S2
VGA cooler.

The card’s cooler is comprised of two copper heatpipes with a series of
friction-fitted, widely spaced fins. The heatsink sits off-center, making
it look crooked. The fins extend past the top edge of the card by a few
millimeters, but if necessary they can be pushed inward to make them flush
with the PCB.


The heatpipes extend past the side edge by 2.6cm. The PCB by itself measures
only 16.8cm. The entire card weighs only 270 grams.


The heatsink on our sample had a slight curve on it — whether this was
intentional or not is difficult to determine. Black plastic guards are positioned
on one end but are too loose to provide real stability. The back panel
features a TV-out and two DVI ports.


The fins are punctured by four rectangular vents that extend the full
length of the card. The heatpipes are about 6mm in diameter.


When placed with the PCB on the bottom (upsidedown), the lack of support at the far end where the heatpipes terminate is conspicuous. The fins in this section
sag downward to the point where they almost touch the capacitors.


The fins are approximately 0.3mm thick with 3.7mm separation between them
— the wide spacing is ideal for passive cooling. Unfortunately, they
are also rather loose, especially near the bottom of the card where there
is no heatpipe for support. The fins in this area can be peeled away from
one another with minimal effort.


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 bolts. The mounting
holes form a square with 4.3cm sides — the same size as the HD 4670
and older cards such as the Radeon X1600 and GeForce 7600 series. If you
prefer aftermarket cooling, compatibility will be good.


The card’s GPU core is exposed and lacks a shim. Four small cubes of rubber
on the cooler’s base keep the core from being crushed from over-tightening.


The cooler has a simple design composed of two copper heatpipes sandwiched
between an aluminum base and mounting plate.


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 State
System Power
DC (Est.)
Ambient temperature: 21°C
Ambient noise level: 11 dBA
System noise level: 12 dBA

PowerColor SCS3 HD4650:

VGA Test Bed: PowerColor SCS3 HD4650
System State
Sys. Fan Speed
Temp 1
Temp 2
System Power
DC (Est.)
12 dBA
CPUBurn + FurMark
CPUBurn + FurMark
15 dBA
CPUBurn + FurMark
18 dBA
Ambient temperature: 21°C.

Testing was initially conducted with the system’s only case fan, a Nexus 120mm,
running at a paltry 7V. In this state, the card’s cooler kept the GPU very cool
when idle: less than 50°C. When the system was stressed, GPU temperatures
stabilized in the low 80’s which is more than adequate for a modern GPU —
they typically have tolerances above 100°C. The card was artifact free during
testing despite the lack of system airflow. When the system fan was sped up
to 9V, GPU temperatures were only marginally affected. At 12V, there was an
impressive 7-8°C improvement.


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)
PowerColor SCS3
HD 4650
Asus EAH3650
ATI Radeon HD 4670

Our PowerColor HD 4650 exhibited slightly lower power consumption than Asus’
passively-cooled HD 3650
when idle (3W), and significant savings at full
load (11W). It’s a nice improvement considering the 4650 is the 3650’s direct
successor. The HD 4670 remains the
king of idle power consumption however, even though it is faster and uses much
of the same software and hardware under the hood.

It’s difficult to pinpoint exactly why the idle power is so high. It may be
the result of differences in chipset implementation by the manufacturer, or
the use of slower, yet more power hungry memory, or a combination of both. It’s
hard to believe either factor alone could result in an extra 12W. We doubt drivers
are the issue — ATI has had plenty of time of to sort out any serious power
issues for their HD 4000 series, especially since they release a new set of
drivers every month. Some form of power management was in effect — the
core/memory speeds lowered to 300/299MHz when the system was idle and during
video playback it alternated between idle and reference speeds.

Video Playback

Video Playback Comparison
Video Clip
HD 4650
HD 3650
HD 4670
Mean CPU
Rush Hour
Coral Reef
Drag Race

As the video decoding hardware is the same in both the HD 3000 and 4000 series,
CPU usage measurements were unsurprisingly similar, passing every test with
ease. The HD 4650’s power consumption during video playback was within a few
watts of its predecessor, the HD 3650, but far behind the ultra-efficient HD
4670. This is due to the higher idle power consumption of the HD 3650 which
carries over to light-load situations like video playback.


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 HD 4650
at techPowerUp,
and HEXUS.
The general consensus is that the HD 4650 is somewhat slower than the HD
, but significantly faster than nVidia’s rival budget part, the GeForce
9500GT. It will deliver decent frame rates on the majority of PC titles if played
at 1280×1024 resolution or lower. Please note most HD 4650 reviews on the web
are not a completely accurate representation of the PowerColor SCS’s performance
due to its rather slow stock memory clock speed — 400MHz compared to the 450/500MHz
samples that most sites have reviewed. However, this particular card is equipped
with 2.0 ns Samsung chips, so they should be able to run at 500MHz without any
difficulty if you decide to overclock.

Video Playback: Video playback was very good. The decoding hardware
is the same featured on the rest of the ATI 3000/4000 series cards.

Cooling: The stock cooler is not solidly constructed, but it is good
enough, adequately cooling the card when our test system’s airflow was set to
ultra-low levels. Because it is passive, it did not generate any noise, nor
did the GPU produce the high-pitched coil whine associated with more performance-oriented

Power Consumption: By our estimates, the HD 4650 requires approximately
15W when idle and up to 28W DC when stressed to the limit. The load figure is
an impressive 11W improvement over its predecessor, the HD
. The idle figure is too high for our liking — a budget card like
this shouldn’t idle at more than 10W. Why it uses so much when its big brother,
the HD 4670, sips only 3W of juice when idle is a bit of a mystery.

The PowerColor SCS HD4650, like most recent graphics cards, has the hardware
necessary to make video playback a breeze. It will not however deliver amazing
3D performance, but it is a decent value considering the price of $70 and its
complete and utter lack of noise. The closest card in its price range is the
HD 4670; a typical actively-cooled HD 4670 costs about $80. Users looking for
better performance and idle power consumption should go with a 4670 (preferably
a passive one). For those who crave silence, the few frames per second you will
lose by selecting the PowerColor SCS HD4650 won’t keep you up at night, and
neither will its fanless cooler.

PowerColor SCS3 HD4650

* Fanless: zero noise!
* Low power consumption on load
* Good HD playback
* Small size


* Flimsy cooler construction
* Idle power consumption a bit high
* Lacking in 3D performance

Our thanks to PowerColor
for the video card sample.

* * *

Articles of Related Interest
Asus 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
Asus EN3650 Silent Graphics

Updated VGA Card/Cooler Test

* * *

this article in the SPCR forums.

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