ASUS GTX 770 DirectCU II OC Review

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With NVIDIA’s GTX 780 dominating the high end and their GTX 760 providing an excellent price / performance ratio within the sub-$300 segment, many have been overlooking the GTX 770. This $400 graphics uses the same GK104 as its spiritual predecessor, the GTX 680 but increases performance through the use of higher Boost clocks and increased memory bandwidth. The result is an adaptable platform that should be appealing to gamers who can’t afford a GTX 780 but want more staying power than a GTX 760 can provide.

ASUS has jumped on the bandwagon with both feet but, unlike their competitors, have narrowly focused their efforts towards a single SKU: the GTX 770 DirectCU II OC. This is an excellent approach since brand confusion can be minimized while gamers get to benefit from slightly lower pricing since ASUS didn’t need to thinly spread their resources in an effort to cover too many different products.

The current generation of ASUS DirectCU II OC cards aren’t known for their sky-high default clock speeds and the GTX 770 is no different. In this case it receives a mere 12MHz Base Clock increase and a 25MHz Boost overclock, neither of which will likely result in a noticeable gameplay improvement. We did however see our card hovering at 1150MHz most of the time with very little movement so performance should be quite respectable in most situations. As with most NVIDIA board partners, ASUS decided to keep the 7Gbps memory at reference clocks since anything higher would have meant limited returns in exchange for potential stability issues.

So what does ASUS’ GTX 770 actually cost? $409 or a mere $10 more than a baseline reference-clocked card. To put this into further perspective, the DirectCU II is $40 less than MSI’s Lightning and costs the same as EVGA’s GTX 770 Superclocked ACX but goes for $10 more than Gigabyte’s faster GTX 770 WindForce OC. As for comparisons against the lackluster 4GB cards, you’ll be saving nearly $40 by deciding to go with the DirectCU II OC. Unfortunately, its clock speeds don’t measure up to these competitors so ASUS will have to hope their component selection and overclocking headroom sets their card apart.

Speaking of component selection, the GTX 770 DirectCU II OC uses much of the same technology as its bigger brother, the spectacular GTX 780 DirectCU II OC. Needless to say, certain parts of this review may sound slightly repetitive as a result.

 

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A Closer Look at the GTX 770 DirectCU II OC

A Closer Look at the ASUS GTX 770 DirectCU II OC

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The GTX 770 version of ASUS’ DirectCU II lineup has a lot in common with its larger sibling, the GTX 780 DirectCU II OC. It utilizes a very similar, distinctive heatsink (though slightly downsized) and measures about 10.7”long so there won’t be any issues fitting into more compact chassis.

Some may be wondering about ASUS’ lineup repetition but we happen to like this approach. Basically, they’ve found an excellent formula and are sticking to it.

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This version of ASUS’ DirectCU II heatsink utilizes a concept that’s been carried over from the previous generation since it works so well. It utilizes a pair of 80mm fans but unlike the GTX 780 version, the CoolTech fan has been left out of the equation, likely to allow this card to hit a lower price point. We’ve consistently found this design to be among the best around so there shouldn’t be any performance loss without the CoolTech unit.

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 GTX 770 version may be a bit smaller in stature but we can’t forget the GK104 core produced significantly less heat than the GK110.

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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Alongside the obvious high-end capabilities of the DirectCU II, ASUS has added some additional horsepower under its hood in the form of four large 8mm heatpipes that make direct contact with the core. The end result is cooling capability well above what an overclocked card would require even though, judging from its stance, this particular heatsink seems to have been designed for a much smaller card. That bit of PCB hanging free of the shroud may not look all that great but we’ll forgive ASUS since it performs spectacularly.

Speaking of overbuilt, the heatsink also hides the DirectCU II’s PWM which is an all-digital affair made up of eight dedicated core phases and another two phases for the GDDR5 memory.

 

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A Closer Look at the GTX 770 DirectCU II OC pg.2

A Closer Look at the GTX 770 DirectCU II OC pg.2

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.

Ironically, ASUS seems to have carried over the PCB en masse from the GTX 780 DirectCU II, components and all. This means the GTX 770 DirectCU II OC is massively overbuilt but we won’t be complaining about that.

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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Flipping the card over, we see that ASUS has continued their approach of utilizing full coverage backplates on all their higher end products. Supposedly this helps stiffen the PCB, preventing the bowing sometimes caused by heavy coolers. It also allows for better heat dissipation.

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The backplate also has a small cutout for voltage read points. We feel that MSI’s implementation of these points is slightly better than ASUS’ approach since they include secondary leads, ensuring you don’t have to go fishing around to find the necessary terminals.

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Our whirlwind tour concludes with the 6+8 pin power connectors and a backplate that’s essentially bone stock, just with some slightly wider openings on the exhaust grille to facilitate outgoing airflow.

 

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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.

ASUS’s DirectCU II heatsink is one of the best around and there’s no better example that the results above. This is by far the lowest temperature we have seen from a GTX 770, which should bode extremely well for overclocking.

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.

While the reference GTX 770 is a quiet card, ASUS brings things to the next level. Their DirectCU II is able to nearly equal the WindForce 3X and Galaxy’s card in acoustics and it handily beats the Lightning. However, at such low decibel levels, you really won’t notice a difference between the top performers here.

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.

 

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Overclocking Results

Overclocking Results

So here we are at the most important part of this review: the overclocking. Like every DirectCU II card, the ASUS GTX 770 comes equipped with a robust suite of tools like GPUTweak to help you increase clock speeds. Unfortunately, ASUS hasn’t bypassed NVIDIA’s stringent limits on Power Limit and voltage but that doesn’t mean this card is a pushover when it comes to achieving higher clock speeds.

With the Power Limit and the Voltage pushed to the maximum allowable settings, we achieved a constant core speed of 1383MHz while the memory finally topped out at 4780MHz. Both of those represent new records among our GTX 770 review samples. Naturally, not all cards will level out at these frequencies but the results are nonetheless encouraging.