Silent Games: Three Unique Graphics Accelerators on Radeon HD 67xx with Passive Coolers

Today we are going to discuss three silent graphics accelerators from the entry-level segment. Do products like that need huge heatsinks after all, and will they be a good fit for gaming rigs?

by Sergey Lepilov
10/05/2011 | 02:40 PM

One year ago, in October 2010, we said goodbye to ATI after testing its entire Radeon HD 5xxx model range. The company itself merged with AMD but its graphics cards have lingered longer than the ATI brand. For its current 6 series AMD uses the good old Radeon HD 5750 and HD 5770 rebranded as HD 6750 and HD 6770, respectively, and equipped with HDMI 1.4a and OpenGL 4.1 support. There are no other differences in specs between these two pairs of graphics cards.


So, AMD/ATI supporters have no choice in the mainstream category other than buying the old ATI Radeon HD 5770/5750s which are still selling or the “new” AMD Radeon HD 6770/6750s. The latter pair is likely to be preferred, so we are going to test a few such cards today. For this review to offer new information compared to our earlier articles about such products, we will take cards from ASUS, Gigabyte and PowerColor which all have one common trait. They have passive cooling. Let’s take a look at each of them and compare their performance.

Testing Participants

ASUS Radeon HD 6770 DirectCU Silent (EAH6770 DCSL/2DI/1GD5)

The first graphics card to be discussed is ASUS Radeon HD 6770 DirectCU Silent. It comes in a large cardboard box with a picture of a knight riding a rambunctious steed.


There is a description of the card’s key features, specs and system requirements on the back of the box. Inside it, there is a soft foam-rubber tray with the graphics card and an additional box with accessories.


The accessories include two power adaptors, one DVI-HDMI adaptor, and a disc with drivers and installation guide.

The card is manufactured in Taiwan and costs about $139. The warranty period is 3 years.

The ASUS Radeon HD 6770 DirectCU Silent has a truly astonishing size. We couldn’t really expect a modest Radeon HD 6770 to ever get that huge! Take a look at it:

The PCB being a mere 183 millimeters long, the graphics card itself measures 290x170x50 millimeters due to the huge cooling heatsink. Thus, it is comparable in length to top-end rather than to mainstream or entry-level products, so we hope this cooling system is going to be most efficient.

The ASUS Radeon HD 6770 DirectCU Silent is equipped with one analog, one DVI and one HDMI output. There is also a vent grid in its mounting bracket:

The card doesn’t support CrossFireX and has no appropriate connectors. There is one 6-pin power connector in its usual location.

According to its specs, the Radeon HD 6770 is expected to be used with a 450-watt or better power supply. The card’s own power consumption is not specified.

The PCB is so simple that we guess it could be shrunk by half and still have enough room for its 3-phase power circuit.

The card features Super Alloy Power technology which ensures 15% performance boost, 35°C cooler operation and 2.5x longer lifespan for its components.

The “performance boost” part looks like a rather meaningless marketing claim to us.

The GPU is manufactured in Taiwan and lacks a protective frame. It incorporates 800 unified shader processors, 40 texture-mapping units and 16 raster operators.

Its clock rate in 3D applications is 850 MHz, in full compliance with AMD's specs. The frequency is lowered to 157 MHz in 2D mode.

The four FCFBGA chips of GDDR5 memory are located on the face side of the PCB. They are manufactured by Hynix Semiconductor and have a total capacity of 1 gigabyte.

The chips are marked as H5GQ2H24MFRT2C, which means a rated clock rate of 5000 MHz and voltage of 1.5/1.35 volts. However, the memory frequency of the ASUS Radeon HD 6770 DirectCU Silent is only 4000 MHz, which is 800 MHz lower than written in AMD's Radeon HD 6770 specs. We don’t know the reason for the reduced memory clock rate, but there seem to be some overclocking potential here. The memory frequency is lowered to 1200 MHz in 2D applications whereas the memory bus is 128 bits wide.

Thus, the ASUS card has the following specs:

Now let’s move on to the most interesting thing about this product. We mean its cooling system, of course.

Really huge for such a modest card, the heatsink is based on four nickel-plated copper heat pipes with a diameter of 8 millimeters. Press-fitted on the pipes, the aluminum fins are 0.35 millimeters thick and placed 2.5 millimeters apart from each other. The whole arrangement is covered with a two-piece metallic casing.

It is likely that you can lower the GPU temperature by a couple of degrees by simply taking the casing off.

One more feature of this cooler is that it uses direct-touch technology. The only problem is that the Juniper GPU is a mere 170 sq. mm large, so it is only touched by the two central heat pipes.

The cooler seems to be overkill for such a modest graphics card. Let's check its performance out, though.

For our temperature test we run the Aliens vs. Predator (2010) benchmark in six cycles with maximum graphics quality settings at 1920x1080 with 16x anisotropic filtering. We use MSI Afterburner 2.2.0 Beta 7 and GPU-Z 0.5.5 as monitoring tools. This test is carried out with a closed system case at an ambient temperature of 24°C. The default thermal interface was replaced with Arctic MX-4 on each card tested for this review.

Here are the results of the ASUS Radeon HD 6770 DirectCU Silent:

The GPU is never hotter than 52°C at peak load and the card is absolutely silent. That’s just a perfect performance. Can this silent card be overclocked? Yes, it can. We boosted our sample to 960/5000 MHz.

The GPU temperature grew by a mere 4°C at that.

There's nothing better we could expect from that card, so let’s move on to the next one.

Gigabyte Radeon HD 6770 Silent Series (GV-R677SL-1GD)

The Gigabyte Radeon HD 6770 Silent Series is shipped in a large box that has a window for you to be able to see some of the card’s heatsink.


As usual, the back of the box is where you can find the product’s description, specs and system requirements. Included with the card are a power adapter (two PATA -> one 6-pin connector), a DVI->D-Sub adapter, a CrossFireX bridge, a disc with drivers and utilities, and an installation guide.

The card is manufactured in Taiwan and has a retail price of about $139. Its warranty lasts for 3 years.

The Gigabyte Radeon HD 6770 Silent Series is but slightly smaller than the above-discussed ASUS and features a fanless cooler, too.

It measures 278x172x42 millimeters and takes up 262 millimeters inside a system case. Besides a vent grid, there is a DVI connector, a DisplayPort and a gold-plated HDMI in its mounting bracket.

As opposed to the ASUS, the Gigabyte card offers one CrossFireX connector for building multi-GPU configurations.

It has a 6-pin power connector in its usual location.

The PCB of the Gigabyte Radeon HD 6770 Silent Series is longer (202 mm) than the ASUS card’s and looks kind of more serious.

Thanks to Gigabyte’s Ultra Durable technology, the card is colder, has higher overclocking potential and consumes less power than the reference Radeon HD 6770.

The GPU of the Radeon HD 6770 Silent Series is the same as we’ve just seen on the ASUS card except for the date of its manufacture.

The rest of the GPU’s characteristics, including its clock rate in 3D and 2D applications, are the same.

The card has GDDR5 memory chips from Hynix Semiconductor on both sides of the PCB:

The chips differ from those of the ASUS card’s and are marked as H5GQ2H24AFR T2C. Their rated clock rate is the same, though. The card’s memory clock rate is 4800 MHz, exactly as in AMD's official specs and 800 MHz higher than the ASUS card's.

Thus, the Gigabyte Radeon HD 6770 Silent Series has the same specs as the reference Radeon HD 6770:

The heatsink of the Silent Cell cooler consists of three parts with four nickel-plated 8mm heat pipes. The cooler’s base is nickel-plated copper, too.

The heatsink has aluminum fins which are 0.25 mm thick and placed 2.5 mm apart from each other. The main heatsink section is pierced with the two central heat pipes whereas the two other sections have one pipe each.

The pipes are flattened out in the cooler’s base and soldered to the latter.


The cooler has contact not only with the GPU but also with the memory chips, via thick thermal pads.

Although not as impressive as the huge cooler from ASUS, the Silent Cell does its job well enough:

The peak temperature of 67°C is quite an achievement for a passive cooler!

The Gigabyte card’s overclocking potential is somewhat lower than the ASUS’s. It was stable at 930/5040 MHz.

Well, that’s not bad for a passively cooled graphics card, especially as the peak GPU temperature increased by a mere 4°C at that, reaching 71°C.

So, the passive cooling systems of the above-discussed Radeon HD 6770s are both highly efficient. Perhaps they are even too efficient for such modest GPUs. Let's see if this is so by installing a small copper heatsink of the Deepcool V4000 cooler on them.



Compared to the original coolers, the ASUS card’s GPU is 12°C hotter (64°C) and the Gigabyte card's GPU is 5°C hotter (72°C). The resulting temperatures are still far from dangerous, though, whereas the Deepcool V4000 heatsink is only half as large as the ASUS DirectCU Silent or the Gigabyte Silent Cell. The fact that the Deepcool heatsink is made from copper may have contributed to its good performance.

We also used the V4000 on a reference ATI Radeon HD 5770 and the latter’s GPU temperature was as high as 81°C.

This indicates that ASUS and Gigabyte select Juniper XT chips capable of working at low voltage and design their PCBs appropriately.

PowerColor Go! Green Radeon HD 6750 Dirt3 Edition (1GBD5-NS3DHG)

PowerColor's card - Go! Green Raden HD 6750 Dirt3 Edition - is going to be liked by eco-conscious users due to its green concept. Its box is quite informative, by the way:


The Go! Green series features reduced power consumption. PowerColor suggests that this contributes to saving our planet’s resources.

The card comes with a minimum of accessories: a power adapter, a disc with drivers, a user manual and a coupon for downloading DiRT 3:

The PowerColor Go! Green Radeon HD 6750 is manufactured in China and costs about $139. We don’t know how long its warranty period is.

The graphics card looks unusual and even ridiculous with its tilted heatsink:

The heatsink seems to be just sloppily installed but this is actually a special feature of the cooling system: the left edge of the bottom heatsink fins press against the card’s DVI outputs and PowerColor didn’t take the trouble of cutting them off to align the heatsink properly. The card looks small after the huge products from ASUS and Gigabyte and measures 202x138x42 mm. Its PCB is 182 millimeters long.

The PowerColor card is equipped with two DVI-I outputs, one HDMI connector and one DisplayPort.

Although the least advanced card in this test session, it features as many as two MIO connectors for building CrossFireX configurations.



It's hard to think of scenarios where you might want to build such CrossFireX subsystems, but the lack of a 6-pin power connector is going to be appreciated by users with low-wattage power supplies.

The card has a 3-phase power circuit. There are aluminum heatsinks on its memory chips.

The Juniper Pro chip was manufactured in Taiwan on the 13th week of 2011.

As opposed to the GPUs of the ASUS and Gigabyte cards discussed above, this one has only 720 unified shader processors, 36 texture-mapping units and 16 raster operators. The GPU clock rate is only 700 MHz in 3D applications and is lowered to 157 MHz in 2D mode. There are heatsinks on the memory chips, so we couldn’t read their markings. We can only tell you that the card’s memory clock rate is 4600 MHz whereas the total memory amount is 1 gigabyte.

PowerColor’s cooling system doesn't have a proper name. It is designed in a very simple way. It has a copper base with four copper heat pipes, 6 millimeters in diameter. There are slim aluminum fins on those pipes, placed 3.5 to 4 mm apart from each other.

The fins are press-fitted on the pipes which are soldered to the base.

Despite the simplicity of design, the cooling system copes well, keeping the GPU temperature under 55°C.

You should keep it in mind that the Juniper Pro's clock rate is 150 MHz lower than the clock rate of the Juniper XT chips the previous two cards are based on. Is the passive cooler of the PowerColor card any good at overclocking? Yes, it is.

The GPU is only 59°C hot when the card is overclocked to 855/4880 MHz.

Now let’s move on to our performance tests.

Technical Specifications

Testbed Configuration and Testing Methodology

All graphics cards were benchmarked in a closed system case with the following configuration:

Besides the three graphics cards described above, we also included the reference ATI Radeon HD 5770 and AMD Radeon HD 6790 graphics cards with 1 GB of video memory onboard:



The former will let us estimate the performance of its successors, the new HD 6770, while the latter will show how far behind the next price and performance stage they are.

In order to lower the dependence of the graphics cards performance on the overall platform speed, I overclocked our 32 nm six-core CPU with the multiplier set at 25x and “Load-Line Calibration” (Level 2) enabled to 4.5 GHz. The processor Vcore was increased to 1.46875 V in the mainboard BIOS:

The 6 GB of system DDR3 memory worked at 1.44 GHz frequency with 7-7-7-16_1T timings and 1.5V voltage. Turbo Boost and Hyper-Threading technologies were disabled during our test session.

The test session started on September 25, 2011. All tests were performed in Microsoft Windows 7 Ultimate x64 SP1 with all critical updates as of that date and the following drivers:

The graphics cards were tested in the today’s most popular resolution of 1920x1080 pixels. The tests were performed in two image quality modes: “Quality+AF16x” – default texturing quality with enabled 16x anisotropic filtering and “Quality+ AF16x+MSAA4(8)x” with enabled 16x anisotropic filtering and full screen 4x anti-aliasing (MSAA) or 8x if the average framerate was high enough for comfortable gaming experience. We enabled anisotropic filtering and full-screen anti-aliasing from the game settings or configuration files. If the corresponding options were missing, we changed these settings in the Control Panels of Catalyst driver. We also disabled vertical synchronization. There were no other changes in the driver settings.

The list of games and applications used in this test session includes two popular semi-synthetic benchmarking suites, one technical demo and 15 games of various genres:

If the game allowed recording the minimal fps readings, they were also added to the charts. We ran each game test or benchmark twice and took the best result for the diagrams, but only if the difference between them didn’t exceed 1%. If it did exceed 1%, we ran the tests at least one more time to achieve repeatability of results.


3DMark Vantage

3DMark 2011

Unigine Heaven Demo

BattleForge: Lost Souls

S.T.A.L.K.E.R.: Call of Pripyat

Left 4 Dead 2

Metro 2033: The Last Refuge

Just Cause 2

Aliens vs. Predator (2010)

Lost Planet 2

StarCraft 2: Wings of Liberty

Sid Meier’s Civilization V

Tom Clancy's H.A.W.X. 2

Crysis 2

Total War: Shogun 2

DiRT 3

World of Planes (alpha)

Hard Reset Demo

Despite the relaxed settings in most of our games, the new Radeon HD 6770 and HD 6750 are not very fast. It is only in a few of them (namely, Left 4 Dead 2, Tom Clancy's H.A.W.X. 2, Sid Meier's Civilization V and Hard Reset) that you can play comfortably at 1920x1080. In the rest of the games from our list you have to lower the resolution or use even simpler graphics quality settings, which can hardly be enjoyable. Thus, the Radeon HD 6770 and, especially, the HD 6750 are not truly gaming products. They are rather meant for multimedia computers that can occasionally be used for some casual gaming.

The diagrams all show the same standings. For example, the Radeon HD 6790 is faster than the Gigabyte Radeon HD 6770 by an average 15% in the FSAA-less mode and by an average 15.2% when we enable FSAA.

The Gigabyte is ahead of the ASUS because the latter's memory clock rate is reduced by 800 MHz. This makes the Gigabyte card 6.6% and 6.8% faster with MSAA turned off and on, respectively.

The PowerColor Radeon HD 6750 is 17 to 21% slower than the Gigabyte Radeon HD 6770 depending on the graphics quality mode.

There is no point in drawing a comparative diagram for Radeon HD 6770 vs. Radeon HD 5770 because these two cards deliver the same performance if clocked at the same frequencies.

Here is a table with the full tests results:


Our tests of Radeon HD 6770 and HD 6750 cards have gone just as expected. These are mainstream cards with rather low gaming performance and almost indistinguishable from the older Radeon HD 5770s and HD 5750s. They are slow in most of today's games, so we can't recommend them to serious gamers. You can’t improve their performance much through overclocking as they don’t have high potential for that. On the other hand, they are affordable and can be a perfect choice for quiet or even completely silent computers. That’s why we’ve selected passively cooled versions of these cards for this review.

The ASUS Radeon HD 6770 DirectCU Silent features the most efficient fanless cooler of the three. With a heatsink that big, you should have no worries about the temperature of the GPU and the graphics card at large. The downside, besides the somewhat higher price compared to the reference card, is that the ASUS version has large dimensions and will not fit into some computer cases, especially compact multimedia ones. This card lacks a CrossFireX connector, has a reduced memory clock rate and comes without any extras among its accessories.

The Gigabyte Radeon HD 6770 Silent Series is the fastest card of this review. It is no more than 15% slower than the more expensive Radeon HD 6790. Its fanless cooler copes well and makes the GPU comfortable even at overclocked frequencies. Like the ASUS card, this one has large dimensions which may make it incompatible with some system cases. We can see no other downsides about the Gigabyte version, though.

The PowerColor Go! Green Radeon HD 6750 Dirt3 Edition is the slowest but also the most economical card among the three. As opposed to the other two, it has no connector for additional power supply. It can be overclocked a little and is much smaller than the ASUS and Gigabyte cards. Thus, it may be the only option for compact system cases among these three products.