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Custom Cooling: Deepcool's Dracula And Arctic's Accelero Xtreme
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1. AMD's Radeon HD 7970: Presenting A Unique Cooling Challenge

The factory-installed GPU coolers used on today’s graphics cards are generally pretty specific. You can't yank the thermal solution from a GeForce GTX 680 and drop it onto a GeForce GTX 660 Ti. In contrast, the companies that design aftermarket coolers try to make them a lot more flexible, accounting for differences in mounting holes, PCB dimensions, and the varying power and memory circuitry found on one card to the next.

Occasionally, AMD or Nvidia modify things even more dramatically, introducing a new design that sends ripples of change through the aftermarket. And that's exactly what happened when the Radeon HD 7970 and 7950 emerged, both of which come with reference coolers that abandon the typically-flat cooling block design. Instead, they use a large, thick shim around the Tahiti GPU, putting it below the surrounding components and relying on a raised contact area for heat transfer away from the graphics processor.

Of course, this cooler design renders AMD's other implementations unusable on the Radeon HD 7900s. It also torpedoes the multitude of aftermarket designs intended to work with as many cards as possible. Most of the companies that manufacture graphics card coolers are used to dealing with dramatic changes, however, and as we wrote this story up, there were already two vendors selling new products to replace the problematic thermal solution covering AMD's Radeon HD 7970: Arctic's Accelero Xtreme 7970 and Deepcool's Dracula 7970. We previewed the Dracula (sold under EKL's name) in Extreme Air Cooling: Our Five-Slot (Quiet) Radeon HD 7970.

In addition, one other manufacturer came up with a way to use a more generic heat sink and fan combination on the Radeon HD 7900-series cards. The EK-VGA Supreme HF HD7970 Cu Adapter from EKWB Cooling Solutions is basically a copper shim that fills the space between a more standard cooling block and the Radeon HD 7970's Tahiti GPU.

Available at frozencpu.com for $4, the adapter is perhaps the least-expensive solution for anyone who already has an aftermarket cooler and wants to re-use it. But how much efficiency do you lose? After all, the adapter is responsible for transferring thermal energy between two surfaces that'd normally be touching, and paste on each.

In order to illustrate the effect of this, we're testing Arctic's Accelero Xtreme III with the copper shim installed and comparing it to the performance of Arctic's Accelero Xtreme 7970. The only functional differences between them are the shape of their cooling blocks and the presence of the shim. 

Let's consider the other coolers we're testing, too:


Reference Radeon HD 7970 Cooler
Arctic Accelero Xtreme 7970/III
Deepcool Dracula 7970
Dimensions:
277(L) × 96(W) × 32(H) mm288(L) × 104(W) × 54(H) mm254(L) × 100(W) × 44(H) mm
Weight:764 grams
653 grams556 grams (heat sink only)
Fans:Single 75 mm  radial fan
Three 92 mm axial fansUp to three 120 mm or two 140 mm axial fans (none included)
Power Cables:
Four-pin graphics card fan headerTwo graphics card fan headers (three- or four-pin)
Dual-fan to single-fan header adapter
Construction:Copper Cooling Block and Cooling FinsCopper Cooling Block, Five 6 mm Copper Heat Pipes, and Aluminum Cooling FinsCopper Cooling Block, Silver Nickel Plating, Six 6 mm Copper Heat Pipes, and Aluminum Cooling Fins
Price
N/A
7970: $80 (Newegg)
III: $78(Newegg)
$75 (MSRP)
not including Fans


AMD's reference cooler for the Radeon HD 7970 doesn't need heat pipes; it instead uses a copper vapor chamber with an array of fins attached. A single 75 mm centrifugal fan pulls air in from the chassis and exhausts out the I/O bracket. Technically, this is the approach we prefer to see taken because it doesn't recirculate hot air inside your case, affecting other components. Unfortunately, the resulting temperatures are merely acceptable, and the noise generated in getting there is pretty unbearable under load.

Do you see the raised GPU contact surface on the vapor chamber? This is what makes the Radeon HD 7900-series cooler unique.


Below is a picture of the naked reference card, showing the thick protective shim surrounding AMD's Tahiti GPU.

2. Arctic Cooling Accelero Xtreme 7970 And III

Aside from the shape of their cooling blocks, the Arctic Accelero Xtreme III and Accelero Xtreme 7970 are essentially identical.

In the shot above, the top cooler is Arctic's generic Accelero Extreme III, flanked by its bundled accessories. The bottom unit is the Accelero Xtreme 7970, surrounded by its complementary hardware. Clearly, the cooling blocks are different.

Both products share similar accessory packages, with a couple of notable changes. The Accelero Extreme III comes with more memory heat sinks to accommodate a wider range of cards, while, for some reason, the Accelero Xtreme 7970 includes a mixed thermal adhesive that requires a catalyst. The fan power cable is designed to plug directly into the graphics card, so the driver software can alter the RPM in response to the thermal load.

A closer look at the 7970-specific cooling block makes the functional difference between these two products even more apparent. Radeon HD 7900-series cards require that the GPU contact area be raised from the rest of the cooler to clear a thick protective shim. The contact area is also turned 45 degrees to match the graphics processor's orientation on the PCB. Both Accelero Xtreme models come with thermal paste pre-applied.

Mounted atop a reference Radeon HD 7970, the card’s dimensions become 12.5 inches long, five inches thick, and 2.25 inches deep. The board weighs in just over two pounds, too.

The assembled graphics card and cooler are just wide enough to chew up more than two expansion slots. AMD's reference cooler already makes the card 11.5-inches long from the factory. And while adding another inch doesn't seem like a big deal, you're going to find that smaller cases simply cannot accommodate the extra length. Enclosures with removable drive bays because particularly attractive here.

The Accelero Xtreme III employs three 92 mm fans and five heat pipes, which are enough to handle up to 300 W of heat dissipating, according to Arctic. Both heat sinks are built on copper cooling blocks and copper heat pipes that run through aluminum fin arrays. Although the fan shrouds are plastic, they're surprisingly sturdy.

Installing the Accelero Xtreme 7970 is easy, despite the perceived difficulty of swapping graphics coolers. First, mix the thermal adhesive and catalyst, apply it to the RAM and VRM heatsinks, and attach them to the card. Next, put the heat sink mounting hardware in the right place on the bracket, and attached that to the card as well.

The Accelero Xtreme III is a little more difficult to install because you have to use EKWB's copper adapter. We found that it was easiest to apply thermal paste to the adapter, place the shim on the GPU, and plop the cooler on top of that.

Arctic's Accelero Xtreme has the same circuit board clearance to the left and right of the GPU. In comparison, Deepcool's Dracula is higher on the right side, and less so on the left. In both cases, though, the vendors require that you glue heat sinks to the voltage regulation circuitry and RAM modules using adhesive, making it difficult to switch them out. As a result, we used Deepcool's low-profile sinks on the memory to the left of the GPU in the name of compatibility.

Here is how the cooler looks installed on a reference card and plugged in to one of our test beds. Because it's so long, the cooler sticks out pretty far beyond the right side of our ATX motherboard.

3. Deepcool Dracula 7970

The Deepcool Dracula 7970 ($75 MSRP) isn't yet available in North America, although the generic version is a lot easier to find.

The Dracula is atypical for a VGA cooler because Deepcool doesn't give you any fans for that $75 entry fee. Whichever coolers you do choose are mounted to an expansion bracket that sits next to the card, rather than attaching directly to the heat sink. Thermal paste for the GPU and thermal adhesive for the RAM and VRM sinks is included, fortunately.

A raised cooling surface differentiates the Dracula 7970 from Deepcool's generic Dracula. Whereas Arctic's Accelero sports a square-shaped pad for making contact with the GPU, Deepcool uses a circular area.

The Dracula features six heat pipes, or one more than Arctic's Accelero Xtreme. The cooler's copper base is nickel-plated and finished to a mirror shine. Copper heat pipes and the aluminum find are nickel-plated as well, resulting in a very shiny sink.

Deepcool's Dracula can accommodate two 140 mm fans or three 120 mm fans. However, we used the two 92 mm fans that came with the company's older V6000, which are rated for 66 CFM of airflow each. We don't anticipate any problems keeping the Radeon HD 7970's Tahiti GPU cool. Driving both fans with power supply leads ensures constant voltage, and, consequently, constant rotational speeds, regardless of load.


As with the Accelero, mounting Deepcool's Dracula 7970 is simple enough once you have AMD's reference cooler disassembled. Thermal adhesive is applied to the RAM and VRM heat sinks, and the cooler attaches directly to the circuit board using existing mounting holes.

The Dracula's heat pipes and cooling fins provide for plenty of clearance on the right side of the GPU. The left side is a lot less roomy due to a tighter heat pipe bend, necessitating lower-profile RAM sinks.

With Deepcool's Dracula mounted to AMD's reference Radeon HD 7970, the assembled card is 11.5 inches long, 4.75 inches wide, 1.75 inches deep, and it weighs just under two pounds. Before jumping to the conclusion that this solution is more compact and lighter than Arctic's competition, remember that the fans and mounting bracket are separate, and we still haven't added them.

Each configuration is going to be different since Deepcool makes you pick your own fans. In our case, the additional hardware measures 11" x 6.5" x 2.75", and adds another 13.8 ounces. With the heat sink and fans combined, the Dracula chews up considerable expansion space, likely killing the potential for CrossFire. On the other hand, the Dracula is about the same length as AMD's stock Radeon HD 7970 when it's installed, so it's more likely to fit horizontally.

4. Test System Setup And Benchmarks

Our testing includes idle and load temperature measurements, in addition to acoustic benchmarks. We're using Battlefield 3 as our graphics load,  with the game running under the Ultra quality preset at 1920x1080 for 10 minutes in the Operation Swordbreaker level. We log temperatures using GPU-Z, and measure noise two feet from the back of the case with a CM-130 SPL meter. Unfortunately, ambient noise is a challenge in our real-world test lab; we recorded 40.5 dB(A).

While the Arctic Accelero Xtreme fans are powered by headers on the graphics card and should vary rotational speed in response to thermal load, Deepcool's Dracula employs power supply or motherboard fan headers. We're using 12 V leads on the motherboard to drive constant RPMs.

We also plan to measure how these coolers handle a GPU overclock to 1100 MHz with a 1.2 V setting. This increase should generate significantly more heat than the stock settings.

Test System
CPU
Intel Core i7-3960X (Sandy Bridge-E), 3.3 GHz @ 4.25 GHz , Six Cores, LGA 2011, 15 MB Shared L3 Cache, Hyper-Threading enabled.
Motherboard
ASRock X79 Extreme9 (LGA 2011) Chipset: Intel X79 Express
Networking
On-Board Gigabit LAN controller
Memory
Corsair Vengeance LP PC3-16000, 4 x 4 GB, 1600 MT/s, CL 8-8-8-24-2T
Graphics
Radeon HD 7970 3 GB GDDR5
Hard Drive
Samsung 470-series 256 GB (SSD)
Power
ePower EP-1200E10-T2 1200 W
ATX12V, EPS12V
Software and Drivers
Operating System
Microsoft Windows 7 x64, Service Pack 1
DirectX
DirectX 11
Graphics Drivers
Catalyst 12.7 Beta
Benchmarks
Battlefield 3
Operation Swordbreaker, Ultra settings, 1920x1080, 10 minutes
5. Benchmark Results: Temperature And Noise

We start with thermal testing to compare AMD's reference Radeon HD 7970 to Arctic's Accelero Xtreme III with EKWB's copper shim, Arctic's Accelero Xtreme 7970, and Deepcool's Dracula 7970.

The Dracula 7970 and Accelero Xtreme 7970 perform almost identically, posting excellent sub-60-degree results under load. When you consider the reference cooler approaches 80 degrees, the improvement is quite impressive.

As we might have expected, adding a shim between the heat sink and GPU takes a toll on efficiency, yielding a mere eight-degree improvement over AMD's vapor chamber, and trailing the Accelero Xtreme 7970 by 14 degrees.

All of the aftermarket coolers generate comparable acoustic results. This is something we would expect from the Dracula, since its power source doesn't change (hence, there is no fan ramp). Nevertheless, the three models perform well enough to shine a spotlight on the reference design's weakness: noise. 

In contrast, we would have thought that Artic's cooler would have demonstrated more variable measurements. We are able to force a 100% duty cycle using AMD's driver, and we know it's possible to spin the Accelero's fans up because we can hear the difference. Thus, we can conclude that the fan profile on the Radeon HD 7970 doesn't impose significantly higher fan speeds until the GPU temperature rises above 68 degrees.

6. Benchmark Results: Overclocking

Next, we increase the clock rate of our card's core to 1100 MHz and increase its voltage to 1.2 V.

The charts are the same, except for the black bar, which illustrates the effect of overclocking on each solution's thermal performance. Arctic's Accelero Xtreme 7970 pulls away from Deepcool's Dracula here, but not by a wide margin. Also, remember that the Dracula can accept larger fans if you're willing to spend more money.

The Acceleo Xtreme III with its copper adapter gets even closer to the reference design, though it still performs slightly better at idle and under load.

AMD's reference cooler becomes even less attractive as the Tahiti core nears 80 degrees. More problematic, though, is how fast the centrifugal fan needs to spin in order to keep the GPU at 79 degrees.

We again see our aftermarket coolers generating low and constant noise levels. In contrast, the reference heat sink and fan combination jumps to an even more unacceptably loud volume under load.

7. High Performance Cooling Options For The Radeon HD 7970

A new vapor chamber design from AMD threw a curve ball at aftermarket cooler vendors. Fortunately, a handful of innovative companies made the changes necessary to counter some of what we think AMD screwed up with its reference Radeon HD 7970 heat sink and fan combination. Arctic, Deepcool, and EKWB are the first three to get hardware into our lab.

Arctic Cooling Accelero Xtreme 7970

Arctic hit a home run with its Accelero Xtreme, a cooler design that we first saw back in 2008. The Accelero Xtreme III is the newest iteration, though the company rebranded it the Accelero Xtreme 7970 with a cooling block modified to fit AMD's Radeon HD 7900-series cards.

The Accelero Xtreme 7970 operates both quietly and coolly. Its fan headers plug right into the graphics card for convenience and control, and the combination effectively brings down temperatures even in the face of aggressive overclocking. An $80 price tag is certainly appropriate in light of what the competition is asking. Our sole concern is that a fully built-up reference card with this cooler is 12.5" long, limiting its use in certain enclosures.

Aside from that one issue, Arctic's Accelero Xtreme 7970 is an excellent way to combat the reference Radeon HD 7970's loud centrifugal fan and vapor chamber-based heat sink. Perhaps more significant is the fact that it seems to be the only natively-compatible Radeon HD 7900-series aftermarket cooling option available for purchase in North America right now.

Deepcool Dracula 7970

Deepcool's generic Dracula is already available in North America. However, its Radeon HD 7970-compatible version is still en route, according to the company. If it were available today, the Dracula's $75 MSRP would be about five dollars less than the Accelero Xtreme 7970. Without fans, though, it quickly gets more expensive.

The Dracula 7970 is a powerful cooler for the Radeon HD 7970. Though it performed slightly below Arctic's Accelero Xtreme 7970 under load, remember that we armed it with a pair of 92 mm fans. The heat sink accommodates as many as two 140 mm or three 120 mm fans, so it's possible to improve this product's cooling potential if you're willing to spend the money. Deepcool's solution also measures 11.5" long, a full inch shorter than the Accelero Xtreme. If you have a space-constrained chassis, that inch could be critical.

On the other hand, the Dracula is very wide once you factor in its cooling fan bracket. It's conceivable to fit one of these inside an enthusiast-oriented enclosure, but two in CrossFire probably isn't going to happen. And with the price of fans added to its total, going the Deepcool route can get pretty expensive.

EK-VGA Supreme HF HD7970 Cu Adapter

EKWB's copper shim makes it possible to use more common coolers with flat contact surfaces and still maintain compatibility with AMD's Radeon HD 7970. Priced at $4 from frozencpu.com, this little adapter is an inexpensive way to help recycle a cooler you have on-hand without needing to drop $80 on something new.

Unfortunately, going that route imposes lower performance than a purpose-built heat sink for AMD's flagship graphics card. Transferring heat through an additional medium, plus two layers of thermal grease, results in GPU temperatures 10 degrees higher under load compared to Arctic's Accelero Xtreme 7970, which we'd consider a native solution.

Making an investment in a high-performance cooler like the Accelero should yield much better thermal and acoustic performance than a reference heat sink and fan combo. Otherwise, why buy it? The EKWB copper shim does the job it's supposed to. However, realizing a moderate gain required a high-end cooler like the Accelero III. A less-capable aftermarket heat sink wouldn't have fared as well, and we would have ended up even closer to what AMD's reference vapor chamber-based implementation was already able to do.