by Yaroslav Lyssenko
05/17/2011 | 11:12 AM
No matter how fast your CPU is and what graphics card you use, you are going to run short of performance sooner or later. Just start to play a movie in your media player, open a dozen websites in your browser, launch your favorite game in windowed mode, and your seemingly high-performance PC will surely indicate you need to upgrade.
Although some of the blame lies with the programmers who fail to optimize their software, your CPU or GPU can also prove to be the limiting factor. Therefore both AMD and Nvidia have developed technologies for uniting multiple graphics cards into a single subsystem. This is a rather cheap way to increase your computer’s graphics performance. It also increases users’ brand loyalty as well as the service life of graphics cards despite the rapid changes in GPU generations. Let’s see what multi-GPU configurations are possible today.
We’re already quite familiar with the top-end cards from both AMD (Radeon HD 6990) and Nvidia (GeForce GTX 590) which represent the low end of this line-up. It is among these solutions that we should look for the fastest graphics subsystems in the world. So, what are our upgrade opportunities? Suppose you bought a Radeon HD 6970 half a year ago and have accumulated some money for an upgrade. If so, you should know that AMD’s multi-GPU technology, as opposed to Nvidia’s SLI, allows combining into a single subsystem not only identical graphics cards. So, today we are going to check out a tandem built out of a Radeon HD 6990 and a Radeon HD 6970.
Nvidia, on its part, is going to be represented by a 3-way SLI configuration consisting of three GeForce GTX 570s. The trio of GF110 chips sports a total of 1440 shader processors, 120 RBEs and a $100 lower price compared to AMD's alternative.
AMD’s Antilles+Cayman duo can boast some tremendous specs, too. Its peak memory bandwidth is as high as 500 GBps, and it has over 4600 ALUs and 288 texture-mapping units. We built our asymmetric CrossFireX tandem with the help from the leading graphics card maker ASUS.
There are two opinions as to whether a top-end graphics card should come with lots of free accessories or not. Some say that a customer is entitled to expect various discount coupons, stickers, posters, or T-shirts when he pays a lot of money for an expensive product, but others hold that it's the graphics card itself that's important and there is no need for extra stuff except for the required minimum of connectors and cables. ASUS seems to agree with the latter opinion.
The ASUS EAH6990/3DI4S/4GD5 comes in a box that is embellished with a picture of an armored rider. Its design is rather conventional but it is the Voltage Tweak sticker that’s meant to make the product a more attractive buy. This technology allows tweaking the card’s GPU voltage in order to increase its overclocking potential (up to 50% as ASUS claims).
As we’ve mentioned above, ASUS has limited the accessories included with the card to the bare minimum of things:
There is nothing extraordinary here except for one adapter which is going to be handy for users of multi-monitor configurations. AMD’s Eyefinity technology for using up to six monitors simultaneously has some limitations. One of them is that you need an active mini-DisplayPort->DVI adapter to connect your third, fourth, fifth and sixth monitor. And one such adapter may cost up to $100.
The ASUS card is hardly different from AMD's reference sample we already tested for our AMD Radeon HD 6990 review. They are in fact identical save for the ASUS logo in the bottom right corner and the somewhat different color of the cooler casing. We shouldn't be upset about the lack of innovations on ASUS's part, though. The fact that ASUS has left the reference Radeon HD 6990 design without any improvements testifies to the high quality of the original PCB design developed by AMD.
The connectivity options include one standard DVI-I connector and as many as four mini-DisplayPorts (compliant with the version 1.2a specification). Thanks to the various adapters included into the box, you shouldn’t have any problems connecting any monitor or TV-set to this graphics card.
ASUS claims this product is exceptionally good at overclocking, so we checked this out in practice.
As a matter of fact, we were rather skeptical about a graphics card with a specified heat dissipation of 375 watts to be any good at overclocking. Indeed, it would get very hot and cause the system to hang up as soon as we tried to increase its voltage from the already high default level of 1.12 volts. We suspect that the default cooling system was not able to cool the power system components effectively at high loads. However, this didn't prevent us from increasing the GPU clock rate to 920 MHz and the GDDR5 clock rate to 6000 MHz. With such settings the card worked for an hour at high load in our stability tests, yet we'd strongly recommend you to ensure additional cooling if you are going to run this card overclocked. The ASUS EAH6990/3DI4S/4GD5 is rather too costly to be used under such risky conditions.
We are going to investigate the gaming performance of ASUS EAH6990 in tandem with Radeon HD 6970 using the following universal testbed:
We used the following ATI Catalyst and Nvidia GeForce drivers:
The ATI Catalyst and Nvidia GeForce graphics card drivers were configured in the following way:
Below is the list of games and test applications we used during this test session:
First-Person 3D Shooters
Third-Person 3D Shooters
Semi-synthetic and synthetic benchmarks
We selected the highest possible level of detail in each game. If the application supported tessellation, we enabled it for the test session.
For settings adjustment, we used standard tools provided by the game itself from the gaming menu. The games configuration files weren’t modified in any way, because the ordinary user doesn’t have to know how to do it. We ran our tests in the following resolutions: 1600x900, 1920x1080 and 2560x1600. Unless stated otherwise, everywhere, where it was possible we added MSAA 4x antialiasing to the standard anisotropic filtering 16x. We enabled antialiasing from the game’s menu. If this was not possible, we forced them using the appropriate driver settings of ATI Catalyst and Nvidia GeForce drivers.
Besides ASUS EAH6990/3DI4S/4GD5, we also tested the following products and tandems:
Performance was measured with the games’ own tools and the original demos were recorded if possible. We measured not only the average speed, but also the minimum speed of the cards where possible. Otherwise, the performance was measured manually with Fraps utility version 3.4.2. In the latter case we ran the test three times and took the average of the three for the performance charts.
About a year ago we wrote that the latest Aliens vs. Predator had come out with very high system requirements. It used to be a very difficult test even for top-end product then. But now it is perfectly playable even at the highest resolution on our configuration built out of an ASUS EAH6990/3DI4S/4GD5 and a Radeon HD 6970. The SLI subsystem with three GeForce GTX 570s cannot beat that result, particularly because it has poor scalability in this test. The addition of a third card doesn’t improve the performance of the SLI configuration much.
We are not sure whether it is worth investing more money into your computer for playing Battlefield: Bad Company 2 Vietnam if you’ve already got a Radeon HD 6970. This graphics card may only call for help at the highest and rather rarely used resolution of 2560x1600. The single ASUS EAH6990/3DI4S/4GD5 easily copes with the highest resolution whereas the 3-way CrossFireX configuration leaves no chance to its opponents in this test.
The game’s graphics engine is too old to be a heavy burden for today’s GPUs. A CrossFireX or SLI configuration is going to be overkill for Call of Duty: Black Ops.
Nvidia’s investments into The Way It’s Meant to Be Played program bear fruit in Crysis 2. Our 3-way CrossFireX configuration is not competitive at all at 1600x900. Although its performance improves at the higher resolutions and it delivers over 60 fps, the ASUS Radeon HD 6990+6970 subsystem can’t catch up with the leaders in this test.
This game is tested with the tessellation option turned on.
We’ve got the same standings as in Crysis 2. The Nvidia-based solutions are unrivalled. It is only at the highest load (2560x1600) that the ASUS tandem overtakes the 3-way GeForce GTX 570 configuration. The Radeons seem to make a better use of the GDDR5 bandwidth there.
This game runs with enabled tessellation.
We can see a familiar picture here. The Nvidia-based solutions meet no competition on the part of the Radeon HD series. But if we put the competitors aside, the single ASUS EAH6990/3DI4S/4GD5 is quite capable of running this game at the highest settings and with a comfortable frame rate. Adding a Radeon HD 6970 to it increases the frame rate by 12 to 18%.
We can see some dramatic competition here. While the Radeon HD 6970 is inferior to every other graphics card and the single ASUS EAH6990/3DI4S/4GD5 makes a draw with its direct rival, the tandem of the mentioned cards comes out the absolute winner of this test.
Lost Planet 2 has very high system requirements, so the Radeon HD 6970 is downright slow in this game. The dual-GPU card from ASUS is the only AMD-based product to deliver a comfortable frame rate. The 3-way CrossFireX tandem improves the frame rate further, yet Nvidia's solutions are overall preferable in this test.
Released earlier this year, Dragon Age II is quite a resource-consuming application, but every graphics solution included into this test session copes with it well enough. You can note that the game engine and the graphics card drivers do not yet work well together when it comes to distributing the total load among three GPUs, so we don’t see the expected performance boost on the 3-way configurations.
We enforced full-screen antialiasing using the method described in our special Mass Effect 2 review.
Mass Effect 2 runs very fast on modern graphics subsystems, every multi-GPU configuration delivering well over 100 fps.
F1 2010 is the hottest test of this review in terms of competition. Our runners are very close to each other at first, so it's hard to make out the winner. It is only at 2560x1600 that the ASUS Radeon HD 6990+6970 configuration leaves Nvidia's products behind. Take note that the 3-way CrossFireX tandem is not much different from the single ASUS EAH6990/3DI4S/4GD5 in this test.
Alas, StarCraft II: Wings of Liberty cannot make good use of the tremendous potential of the Antilles+Cayman pair. The 3-way CrossFireX tandem is a mere 8% ahead of the single ASUS EAH6990/3DI4S/4GD5. You can achieve the same performance boost by simply overclocking the latter. So, there is no significant difference between the dual- and triple-chip solutions from AMD in this game. It's even funnier with Nvidia's products: we've got three different Nvidia-based graphics subsystems delivering the same performance!
A patch has been recently released for this game, adding to its graphics engine features. It hasn’t affected the speed of the game much, though. Developed within the framework of AMD’s Gaming Evolved program, Total War: Shogun 2 naturally prefers AMD-based products. The 3-way CrossFireX tandem is the leader of this test but its advantage over the other cards shrinks as we switch to higher display resolutions. The 3-way GeForce GTX 570 SLI fails due to poor support on the side of the graphics driver.
We minimize the CPU’s influence by using the Extreme profile (1920x1200, 4x FSAA and anisotropic filtering). We also publish the results of the individual tests across all resolutions.
Top-end graphics subsystems are often used to setting new records in synthetic benchmarks. A 3DMark Vantage score of 10,000 points used to be considered high just some time ago, but now the ASUS Radeon HD 6990+6970 tandem stops at 25,000 points and is even overtaken by the 3-way GeForce GTX 570 SLI.
3DMark Vantage shows different compatibility with multi-GPU technologies. Nvidia’s trio doesn’t enjoy a large advantage over the 2-way GeForce GTX 580 SLI or over the GeForce GTX 590. In the AMD camp, adding the Radeon HD 6970 to the ASUS EAH6990/3DI4S/4GD5 increases the latter’s performance by almost 50%, and the resulting 3-way CrossFireX tandem wins the test at high resolutions.
We use the Extreme profile here. As opposed to 3DMark Vantage, this profile has a resolution of 1920x1080 pixels.
3DMark11 prefers the graphics architecture with higher computing resources which is the 3-way CrossFireX configuration. The advantage over the 3-way GeForce GTX 570 SLI is less than 100 points, yet that's enough to claim victory in this test.
This benchmark makes wide use of tessellation to render the surface of the earth. The number of polygons per one frame can be as high as 1.5 million!
This test illustrates the importance of the graphics driver. The Antilles+Cayman duo copes with the test well and challenges the Nvidia-based products which have been traditionally strong here. If you take note of the performance of the SLI configuration, you can see that it fails due to the ForceWare driver.
We use Normal tessellation in this test.
Tessellation is crucial in this test, so Nvidia’s product comes out the winner due to its better tessellation subunit. The 3-way GeForce GTX 570 SLI only wins at 1600x900, though. The ASUS Radeon HD 6990+6970 tandem catches up with the leader and matches its performance at the higher resolutions.
The number one rule for choosing a multi-GPU configuration is to make up your mind beforehand about what games you are going to run on it because the performance of any modern multi-GPU solution depends on the graphics driver’s ability to distribute the load among the GPUs effectively in the particular game.
If you’ve got a single Radeon HD 6970 and want to give your computer a dramatic boost by adding an ASUS EAH6990/3DI4S/4GD5 to it, the $699 investment will give you a performance gain of 90% on average and up to 200% in individual tests at 1600x900. Nvidia’s alternative, the 3-way GeForce GTX 570 SLI, is slightly faster than the 3-way CrossFireX tandem on average at this resolution.
The higher display resolution puts the graphics subsystem resources to better use. The ASUS Radeon HD 6990+6970 tandem has excellent results. It is 100% faster than the single Radeon HD 6970 and 30% ahead of the dual-chip Radeon HD 6990. Nvidia's 3-way GeForce GTX 570 SLI delivers the same performance as the 3-way CrossFireX configuration, though.
Of course, it is the resolution of 2560x1600 that’s the most relevant for such premium-class graphics subsystems and the ASUS Radeon HD 6990+6970 tandem enjoys a larger advantage over the junior solutions here. It is 130% faster than the single Radeon HD 6970, for example. The 3-way GeForce GTX 570 SLI loses its ground and falls an average 3% behind the 3-way CrossFireX, losing five out of the 17 tests.
So, which 3-way graphics subsystem is better? It’s hard to answer definitely since the competition is as tough in the premium sector as among much more affordable products. The ASUS Radeon HD 6990+6970 configuration takes less room in the system case, consumes somewhat less power and does not need a heap of power cables.
On the other hand, the 3-way GeForce GTX 570 SLI is almost as fast as the CrossFireX tandem in sheer performance whereas the mentioned benefits are not so crucial after all. If you are ready to spend $1000 for your gaming computer, you will surely buy a roomy system case and a PSU with lots of power cables. In fact, the choice may be made on the basis of your preferences to the particular brand.
So, if you’ve already got bored with your Radeon HD 6970 and want to get new thrills by adding a Radeon HD 6990 to it, you won't be disappointed with the performance of the resulting tandem, especially when you use it together with a high-resolution monitor.
The ASUS EAH6990/3DI4S/4GD5 is a copy of AMD’s reference card which has already got a reputation of a well-made high-performance product. We don’t think that ASUS engineers might introduce anything to make it even faster or more desirable for some other reason.
Yes, there is no limit to perfection, but sometimes it is more important to stop at a good moment and Asus did exactly that. ASUS EAH6990/3DI4S/4GD5 is going to cope with anything you can throw at it. It even has some overclocking potential in case you need a little extra speed.