ASUS GTX 780 DirectCU II OC Review

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The ASUS GTX 780 DirectCU II OC has some big shoes to fill. Its predecessor, the GTX 680 of the same name was one of the best previous-generation cards we tested and highlighted the ways ASUS leveraged their engineering division to create something special.

Amidst the nearly endless number of custom GTX 780 cards, the DirectCU II OC is still quite unique. It uses ASUS’ excellent custom heatsink design, some advanced PWM technologies, a nearly endless list of features and higher clock speeds. But, most importantly of all, the GTX 780 DirectCU II OC goes for just $669 or $20 more than a reference version.

That may still be a completely unaffordable level for the vast majority of gamers but when you consider a TITAN still retails for $999 and pre-overclocked GTX 780s have flirted with its performance bracket, ASUS seems to have packed a good amount of value into their card. Plus, it’s also $10 less expensive than Gigabyte’s WindForce OC the same price as EVGA’s SC ACX edition.

There is of course a reason behind ASUS’ fair pricing structure for this card: while it is overclocked, the base and Boost frequencies aren’t that much higher than a reference version. However, there’s more here than what first meets the eye. Due to the advanced heatsink design, there’s quite a bit of thermal overhead, something which GeForce Boost 2.0 can take full advantage of. That means the average clock speed we observed was a constant 1032MHz, which is within spitting distance of Gigabyte’s 1071MHz.

On the memory side of things, we have the usual affair with 3GB of reference-clocked GDDR5. Supposedly there’s a good amount of overclocking headroom here so the standardized frequency isn’t all that concerning.

Since ASUS has packed an absolute laundry list of features into their GXT 780 DirectCU II OC, we’re going to go about this review in a slightly different manner. Instead of jamming everything onto the first page we’ll be going over every unique addition separately and let me tell you, there are a lot of them.

 

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A Closer Look at the ASUS GTX 780 DirectCU II OC

A Closer Look at the ASUS GTX 780 DirectCU II OC

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While the DirectCU design’s exterior characteristics haven’t changed all that much since its inception, this version has a slightly more aggressive look that also flows quite well over the heatsink shroud. With that being said, that heatsink plays a major role in this card’s appeal and is a keystone in ASUS’ “cooler, quieter and more reliable” approach.

At 11.3” long, the GTX 780 DirectCU II OC isn’t all that much longer than the reference card, a fact that will surely be good news to anyone with a compact enclosure. This also means that ASUS has been able to engineer their heatsink in a way that ensures a small footprint without sacrificing performance.

One area where this card is larger is width, which at nearly 6” indicates that additional space was needed for both the DirectCU II and the expanded PWM.

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The “cooler” part of this equation is partially taken care of by one of ASUS’ new hybrid CoolTech fans which feature wide-angle, directional airflow characteristics which speed up heat dispersion from the heatsink.

At this point you may be wondering why only a single CoolTech fan has been installed while the other uses a typical axial design. It may seem like an odd choice but the axial fan’s vertical airflow directionality will actually move hot towards the front-mounted CoolTech unit which will then push it out the backplate. The layout is actually quite brilliant since it can act as a quasi-blower style setup.

As with many other ASUS graphics cards, the DirectCU II uses dust proof fan technology which essentially seals the bearing area, preventing particulate matter from entering. This is supposed to help increase the fan’s average life up to 10,000 hours (for a total MTBF of 50,000 hours) or approximately 25% longer than a typical axial design without this addition.

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ASUS’ DirectCU II heatsink is able to capitalize upon the fans’ capabilities by giving them a fin array with minimal airflow restrictions and a surprisingly thin design. This last point is particularly important since not that long ago, these cards were critiqued for their overly large triple-slot layout. Now, additional cooling capacity has been built into a high density fin array.

The approach taken here is an interesting one since ASUS has been able to dissect their custom heatsink into five distinct yet critical components. There is a pair of fans, a shroud to direct airflow, the main fin array with its core contact plate, a metal stiffener that prevents PCB flex and a rear heatsink for more efficient heat distribution.

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The star of this show is the large heatpipe / fin array combination that sits atop the GK110 core. In order to reduce temperatures it uses a four 8mm and a single massive 10mm heatpipes (all of which are copper) that make direct contact with the core. That single 10mm heatpipe allows for 40% greater heat transfer capabilities versus a typical 8mm pipe.

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A heatsink can have a ton of heatpipes but they’d all be for nothing if they’re paired up with a small fin array. ASUS has deftly avoided this potential issue by designing an assembly that’s over twice the size of the one you’ll find on the reference version. This large surface area with its densely packed fin array will allow for much lower temperatures alongside a lower acoustical range since the fan’s won’t have to spin up to crazy speeds in an effort to keep things in check.

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That back-mounted secondary heatsink we alluded to before covers the entire PCB and is fabricated out of high-yield aluminum. Perforations have been added near the rear area which encourages airflow to various components and the SAP CAP mounted behind the core.

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As with many of these enthusiast-level GTX 780 cards, ASUS has added individual voltage read points. They are conveniently placed along the PCB’s outer edge and are quickly accessible for multimeter probes.

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Connector-wise, there really aren’t any surprises here with a stock I/O offering and compatibility with triple SLI. Even the 6+8 pin layout from the reference card remains the same, though ASUS has inverted the connectors to allow more room for the heatsink and even added two small LEDs that glow green when a successful connection is made.

 

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Under the Heatsink; SAP Components Galore

Under the Heatsink; SAP Components Galore

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ASUS has gone all out in the design department for their GTX 780 DirectCU II OC and there’s no other area more evident of this focus than the PCB’s component selection. It all starts with massive goliath-like PCB that’s been expanded to house an 8 phase GPU all-digital PWM alongside two dedicated phases for the GDDR5 memory. That’s a major distinguishing factor since very few competitors (other than the Galaxy HoF and MSI Lightning) can lay claim to a similar feature set.

We also can’t forget that ASUS has taken it upon themselves to offer up a ground-up custom design. All of the components and PCB layout are of their own making which means a strict control over quality and longevity.

One of the cornerstones of ASUS’ approach is what they call Super Alloy Power or SAP components. When taken at face value, it is no different from MSI’s Military Class or Gigabyte’s Ultra Durable initiative but there’s much more to it.

Like its competitors’ options, SAP aims to equip ASUS’ higher end graphics cards with PWM components that provide better performance, lower operating temperatures and a longer lifespan than a reference design. However, SAP actually takes things to the next level by specifying distinct, ASUS-designed items which are spread across the MOSFETs, capacitors and chokes. Super Alloy Power isn’t just a fancy marketing term either since there are some noteworthy enhancements packed into this design.

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The three aforementioned component categories (caps, MOSFETs and chokes) play an important part role in GPU design and power delivery. In this case, the chokes ASUS has chosen use a special reinforced core which not only reduces coil whine but also delivers superior performance, improved power output, reduced temperatures and additional protection against electronic interference. To a layman, these aspects may not have a direct impact upon performance but everything from overclocking stability to the card’s lifespan may be improved.

Other than the chokes, SAP also includes capacitors with a titanic 150,000 hour MTBF that increases the maximum voltage threshold and power output by about 30%. There’s also the upgraded MOSFETs the lower operating temperature and enhance power delivery, thus enhancing overclocking headroom. ASUS has even installed a specialized SAP CAP behind the GPU core which further augments input stability.

So what is the result of all of this haute technology? A number of things of which some may be experienced firsthand while others are slightly more intrinsic in nature. For example, as we can see above, the enhanced chokes and MOSFETs have a significant impact upon PCB temperatures.

With all of the enhancements, component-destroying ripple has also been decreased by a significant amount, particularly when the card is working at higher voltages. Even efficiency has been given a boost.

On the flip side of that coin, many of ASUS’ other features will be stymied by NVIDIA’s GPU Boost limits which clamp down hard on overclocking headroom. Granted, SAP will likely allow you to remain at higher frequencies well into the card’s life but initially, very few will experience much difference between this card and a reference version.

For anyone who wants to push their card to the limit via custom BIOSes that throw out NVIDIA’s predetermined limits, ASUS’ SAP will likely be invaluable. It’s simply up to the end user to determine how far they’re willing to push things.

 

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Test System & Setup

Main Test System

Processor: Intel i7 3930K @ 4.5GHz
Memory: Corsair Vengeance 32GB @ 1866MHz
Motherboard: ASUS P9X79 WS
Cooling: Corsair H80
SSD: 2x Corsair Performance Pro 256GB
Power Supply: Corsair AX1200
Monitor: Samsung 305T / 3x Acer 235Hz
OS: Windows 7 Ultimate N x64 SP1


Acoustical Test System

Processor: Intel 2600K @ stock
Memory: G.Skill Ripjaws 8GB 1600MHz
Motherboard: Gigabyte Z68X-UD3H-B3
Cooling: Thermalright TRUE Passive
SSD: Corsair Performance Pro 256GB
Power Supply: Seasonic X-Series Gold 800W


Drivers:
AMD 13.8 BETA
NVIDIA 326.80


*Notes:

- All games tested have been patched to their latest version

- The OS has had all the latest hotfixes and updates installed

- All scores you see are the averages after 3 benchmark runs

All IQ settings were adjusted in-game and all GPU control panels were set to use application settings

The Methodology of Frame Testing, Distilled

How do you benchmark an onscreen experience? That question has plagued graphics card evaluations for years. While framerates give an accurate measurement of raw performance , there’s a lot more going on behind the scenes which a basic frames per second measurement by FRAPS or a similar application just can’t show. A good example of this is how “stuttering” can occur but may not be picked up by typical min/max/average benchmarking.

Before we go on, a basic explanation of FRAPS’ frames per second benchmarking method is important. FRAPS determines FPS rates by simply logging and averaging out how many frames are rendered within a single second. The average framerate measurement is taken by dividing the total number of rendered frames by the length of the benchmark being run. For example, if a 60 second sequence is used and the GPU renders 4,000 frames over the course of that time, the average result will be 66.67FPS. The minimum and maximum values meanwhile are simply two data points representing single second intervals which took the longest and shortest amount of time to render. Combining these values together gives an accurate, albeit very narrow snapshot of graphics subsystem performance and it isn’t quite representative of what you’ll actually see on the screen.

FCAT on the other hand has the capability to log onscreen average framerates for each second of a benchmark sequence, resulting in the “FPS over time” graphs. It does this by simply logging the reported framerate result once per second. However, in real world applications, a single second is actually a long period of time, meaning the human eye can pick up on onscreen deviations much quicker than this method can actually report them. So what can actually happens within each second of time? A whole lot since each second of gameplay time can consist of dozens or even hundreds (if your graphics card is fast enough) of frames. This brings us to frame time testing and where the Frame Time Analysis Tool gets factored into this equation.

Frame times simply represent the length of time (in milliseconds) it takes the graphics card to render and display each individual frame. Measuring the interval between frames allows for a detailed millisecond by millisecond evaluation of frame times rather than averaging things out over a full second. The larger the amount of time, the longer each frame takes to render. This detailed reporting just isn’t possible with standard benchmark methods.

We are now using FCAT for ALL benchmark results.


Frame Time Testing & FCAT

To put a meaningful spin on frame times, we can equate them directly to framerates. A constant 60 frames across a single second would lead to an individual frame time of 1/60th of a second or about 17 milliseconds, 33ms equals 30 FPS, 50ms is about 20FPS and so on. Contrary to framerate evaluation results, in this case higher frame times are actually worse since they would represent a longer interim “waiting” period between each frame.

With the milliseconds to frames per second conversion in mind, the “magical” maximum number we’re looking for is 28ms or about 35FPS. If too much time spent above that point, performance suffers and the in game experience will begin to degrade.

Consistency is a major factor here as well. Too much variation in adjacent frames could induce stutter or slowdowns. For example, spiking up and down from 13ms (75 FPS) to 28ms (35 FPS) several times over the course of a second would lead to an experience which is anything but fluid. However, even though deviations between slightly lower frame times (say 10ms and 25ms) wouldn’t be as noticeable, some sensitive individuals may still pick up a slight amount of stuttering. As such, the less variation the better the experience.

In order to determine accurate onscreen frame times, a decision has been made to move away from FRAPS and instead implement real-time frame capture into our testing. This involves the use of a secondary system with a capture card and an ultra-fast storage subsystem (in our case five SanDisk Extreme 240GB drives hooked up to an internal PCI-E RAID card) hooked up to our primary test rig via a DVI splitter. Essentially, the capture card records a high bitrate video of whatever is displayed from the primary system’s graphics card, allowing us to get a real-time snapshot of what would normally be sent directly to the monitor. By using NVIDIA’s Frame Capture Analysis Tool (FCAT), each and every frame is dissected and then processed in an effort to accurately determine latencies, frame rates and other aspects.

We've also now transitioned all testing to FCAT which means standard frame rates are also being logged and charted through the tool. This means all of our frame rate (FPS) charts use onscreen data rather than the software-centric data from FRAPS, ensuring dropped frames are taken into account in our global equation.

 

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Assassin’s Creed III / Crysis 3

Assassin’s Creed III (DX11)

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The third iteration of the Assassin’s Creed franchise is the first to make extensive use of DX11 graphics technology. In this benchmark sequence, we proceed through a run-through of the Boston area which features plenty of NPCs, distant views and high levels of detail.


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Crysis 3 (DX11)

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Simply put, Crysis 3 is one of the best looking PC games of all time and it demands a heavy system investment before even trying to enable higher detail settings. Our benchmark sequence for this one replicates a typical gameplay condition within the New York dome and consists of a run-through interspersed with a few explosions for good measure Due to the hefty system resource needs of this game, post-process FXAA was used in the place of MSAA.


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Dirt: Showdown / Far Cry 3

Dirt: Showdown (DX11)

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Among racing games, Dirt: Showdown is somewhat unique since it deals with demolition-derby type racing where the player is actually rewarded for wrecking other cars. It is also one of the many titles which falls under the Gaming Evolved umbrella so the development team has worked hard with AMD to implement DX11 features. In this case, we set up a custom 1-lap circuit using the in-game benchmark tool within the Nevada level.


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Far Cry 3 (DX11)

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One of the best looking games in recent memory, Far Cry 3 has the capability to bring even the fastest systems to their knees. Its use of nearly the entire repertoire of DX11’s tricks may come at a high cost but with the proper GPU, the visuals will be absolutely stunning.

To benchmark Far Cry 3, we used a typical run-through which includes several in-game environments such as a jungle, in-vehicle and in-town areas.


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Hitman Absolution / Max Payne 3

Hitman Absolution (DX11)

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Hitman is arguably one of the most popular FPS (first person “sneaking”) franchises around and this time around Agent 47 goes rogue so mayhem soon follows. Our benchmark sequence is taken from the beginning of the Terminus level which is one of the most graphically-intensive areas of the entire game. It features an environment virtually bathed in rain and puddles making for numerous reflections and complicated lighting effects.


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Max Payne 3 (DX11)

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When Rockstar released Max Payne 3, it quickly became known as a resource hog and that isn’t surprising considering its top-shelf graphics quality. This benchmark sequence is taken from Chapter 2, Scene 14 and includes a run-through of a rooftop level featuring expansive views. Due to its random nature, combat is kept to a minimum so as to not overly impact the final result.


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Tomb Raider

Tomb Raider (DX11)

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Tomb Raider is one of the most iconic brands in PC gaming and this iteration brings Lara Croft back in DX11 glory. This happens to not only be one of the most popular games around but it is also one of the best looking by using the entire bag of DX11 tricks to properly deliver an atmospheric gaming experience.

In this run-through we use a section of the Shanty Town level. While it may not represent the caves, tunnels and tombs of many other levels, it is one of the most demanding sequences in Tomb Raider.

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Temperatures & Acoustics / Power Consumption

Temperature Analysis

For all temperature testing, the cards were placed on an open test bench with a single 120mm 1200RPM fan placed ~8” away from the heatsink. The ambient temperature was kept at a constant 22°C (+/- 0.5°C). If the ambient temperatures rose above 23°C at any time throughout the test, all benchmarking was stopped..

For Idle tests, we let the system idle at the Windows 7 desktop for 15 minutes and recorded the peak temperature.

When looking at these results, only one word springs to mind: incredible. These are the absolute lowest results we have seen from a GTX 780 to date and they allow for a ton of overclocking headroom before GPU Boost’s 81°C cap is hit. ASUS couldn’t have designed a better heatsink.

Acoustical Testing

What you see below are the baseline idle dB(A) results attained for a relatively quiet open-case system (specs are in the Methodology section) sans GPU along with the attained results for each individual card in idle and load scenarios. The meter we use has been calibrated and is placed at seated ear-level exactly 12” away from the GPU’s fan. For the load scenarios, a loop of Unigine Valley is used in order to generate a constant load on the GPU(s) over the course of 15 minutes.

Like with the temperature results, ASUS is really brining things to the next level here. Their fans are whisper quiet even when the core is operating at full tilt. Even the quietest case fans will drown these out so you can keep gaming in relative peace.

System Power Consumption

For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we used 15 minutes of Unigine Valley running on a loop while letting the card sit at a stable Windows desktop for 15 minutes to determine the peak idle power consumption.

Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter.

With ASUS playing up the supposed efficiency of their Super Alloy Power PWM design, we were hoping for some good results here and once again the DirectCU II OC didn’t disappoint. This GTX 780 doesn’t consume all that much more power than a reference card while outperforming it by a sometimes-significant amount.

 

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Overclocking Results

Overclocking Results

For many current generation GeForce graphics cards, overclocking is where there rubber meets the road and abruptly stops. You see, NVIDIA has put a number of restrictions on overclocking which their board partners are forced to follow. Again and again we’ve run afoul of these and as a result our efforts to wring additional performance out of certain cards have been met with frustration. Even when using ASUS’ excellent GPU Tweak utility.

ASUS’ GTX 780 DirectCU II naturally adheres to the NVIDIA-dictated “laws of GPU physics” but that doesn’t mean it can’t hit some frequency levels we’ve thus far struggled to achieve. The trick to overclocking this card is to balance its strengths against the areas where the mere 106% Power Limit and Voltage Limit will typically play havoc with clock speeds. Basically, it goes like this: cooler-running transistors require less power to operate and ASUS has equipped this card with an outstanding heatsink.

With that in mind, we cranked up the fan speed to 70% (which produced a surprisingly limited amount of noise) and went to work on the core frequency and voltages with the Power Limit maxed out 106%. Unfortunately, anything above the +25mV mark caused the GTX 780 DirectCU II OC to run into the Power Limit before we could even max out voltage. This meant clock speeds were held back as GPU Boost 2.0 struggled to achieve a balance between its various elements.

Since the core temperatures never climbed above the 75°C mark (now THAT’S something to brag about!) we were able to hit a constant speed of 1213MHz with some rare instances showing 1235MHz. Even the memory joined in on the fun by going to an astronomical 7008MHz. As you might expect, the performance numbers were out of this world.