Videocard Image-Quality Shootout

Posted 01/28/2008 at 5:48pm | by Michael Brown

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We rely mostly on objective benchmarks here at Maximum PC, especially when it comes to evaluating videocards. It’s just easier to defend a verdict that’s based on frames per second because—assuming you’re using a good benchmark and the same parameters—you’ll get pretty much the exact same number with every run.

Of course, frame rate isn’t everything, especially if your PC’s primary mission is something other than gaming. If you use your computer for editing video, watching movies, or manipulating digital photographs, you’re much more interested in visual quality. Judging image quality, however, is much more difficult because it’s necessarily a subjective task.

But we’ve been hearing whispers from sources (who wish to remain anonymous, although we can tell you they represent neither AMD nor Nvidia) that ATI GPUs deliver better image quality than what Nvidia has to offer. ATI product managers made a similar claim while rolling out their AVIVO technology initiative, but neither AMD nor Nvidia have had much to say on the topic for quite some time.

Never ones to let sleeping dogs lie, we decided it was time to settle this issue Maximum PC style: We gathered a bunch of our game-playing, movie-watching, photo-editing colleagues and challenged them to a blind taste test. Would the consensus opinion favor AMD or Nvidia, or would anyone be able to discern any differences at all?

How We Tested

A lot of thought went into developing our test methodology. Here are the details regarding the hardware and software we used, along with our rationale for making these choices.

THE HARDWARE

The fact that we awarded HP’s VoodooPC-designed Blackbird 002 a 7 verdict in our Holiday 2007 issue didn’t dissuade us from using the innovative rig for this challenge. Although we panned the particular eval unit we received because it included Radeon HD 2900 XT cards in CrossFire, instead of the much faster GeForce 8800 GTX or Ultra cards, we lavished praise on its innovative industrial design, supremely quiet cooling apparatus, and—most significantly—its ability to run either two Nvidia cards in SLI or two Radeon cards in CrossFire on an SLI motherboard.

HP's Blackbird 002 enabled us to compare SLI and CrossFire videocard performance in otherwise identical rigs.

That unprecedented flexibility prompted us to request a matched set of Blackbirds from HP, each equipped with an Intel Core 2 Extreme QX6850 quad-core CPU (3GHz, overclocked to 3.33GHz), 2GB of Corsair Dominator XMS2 DDR2 RAM, and three Western Digital 160GB Raptor hard drives (in RAID 0). All of this was plugged into an Asus Striker Extreme Nvidia nForce 680i SLI motherboard.

We asked HP to configure one rig with two ATI Radeon HD 3870 cards in CrossFire and one with two Nvidia GeForce 8800 Ultra cards in SLI. We also asked HP to provide us with two additional cards from each camp (more on that later). We chose the Radeon HD 3870 cards because they’re based on the best GPU that AMD currently has to offer.

We soon realized we’d made a mistake in configuring the machine with 8800 Ultra cards, however, because those cards don’t support HDCP on both links in their dual-link DVI connectors. Without that, you can’t view encrypted HD video content in high definition on a 30-inch LCD (our screen choice for this challenge). The other problem was that the Ultras were too fast for our purposes: We couldn’t come close to synchronizing frame rates in our gaming tests on the ATI and Nvidia machines.
So we moved down to Nvidia’s 8800 GT. It supports HDCP on both links, the frame buffers on the cards we selected are the same size (512MB) as those on the 3870s, and the ATI and Nvidia cards would run our game benchmark at approximately the same speed (our objective being image-quality comparison, not frame-rate measurement).

We paired the Blackbirds with identical HP LP3065 30-inch LCD monitors. We set the brightness controls to the same values, and then calibrated the two monitors using a Pantone HueyPro calibration kit.

THE BENCHMARKS

We chose the cinematic built-in benchmark from World in Conflict to test DirectX 10 gaming performance (we remain unimpressed with Vista, but these GPUs were ostensibly designed for DirectX 10 performance). In order to achieve the smoothest frame rate, we reduced the game’s resolution to 1280x800, set most of its values to medium, and turned off the water-reflection settings. This enabled both cards to run the demo at about 40 frames per second.

We had our test subjects view a sequence from the HD DVD disc Blue Planet to evaluate high-definition video quality. This IMAX film features spectacular clips filmed from above and around the planet, which made for a much more diverse viewing experience than a Hollywood movie would have provided.

For our final test, we asked our test subjects to examine a very high definition (2592x3888 pixels) portrait of a female model, shot with a Canon EOS-1D Mark III (we obtained the photo from Canon’s website). See representative samples from each of our tests on the next page.

THE TEST SUBJECTS

We recruited our 21 evaluators from the ranks of the Future US staff, including editors and art directors from other print and online publications. We chose these individuals because of their in-depth expertise at evaluating image quality in all three of our test criteria.

THE TESTS

We set up the two Blackbirds in the Maximum PC Lab, with the monitors placed side by side, at the same height and at the same angle to the viewer. We sat each test subject on a rolling stool, so he or she could easily roll back and forth between the two monitors in order to avoid visual distortion caused by off-axis viewing angles.

The test administrator told each subject only that we were evaluating image quality; the subjects were not informed that we were evaluating videocards or any other hardware. Neither of the test rigs were outfitted with speakers. The test administrator asked each subject to express a preference for the image displayed on monitor A or monitor B or to express no preference for either. Subjects were expressly told that “no preference” was a perfectly valid opinion, but if they did choose A or B, they were asked to explain their rationale for that decision.

To reduce random chance, we conducted nine tests with our CrossFire system labeled as A and our SLI system labeled as B. We reversed the order for our next six tests, and we established two control groups of three tests each in which both A and B were CrossFire and then both A and B were SLI.