Videocard Buyers Guide

Blessed be the forces of competition. There’s never been a better time to shop for a new videocard.

By Will Smith and Michael Brown

Poor Nvidia. AMD is putting on the price squeeze from one side, while Intel is crimping its SLI style on the other.

It’s not that the two companies are colluding to pressure the once high-flying GPU manufacturer, it’s just that AMD’s Radeon HD 4000-series performs a whole lot better than anyone expected (and is much cheaper to manufacture than what Nvidia is building).

Meanwhile, Intel’s brand-new Core i7 CPU has earned so much positive buzz that Nvidia had to cry “Uncle!” and allow Intel to support SLI in its X58 chipset (the X58 supports CrossFire, too).

Nvidia’s top-shelf GPU, the GeForce GTX 280, isn’t a bad graphics processor, but AMD’s Radeon HD 4870 comes close enough that Nvidia was forced to slash its prices in order to remain competitive.

If you’re not building a gaming rig, there’s absolutely no reason why you shouldn’t use a cheaper videocard based on one of AMD’s GPUs. And if you are a hard-core gamer, you’ll want to take a look at Radeon HD 4870 X2 cards, which put two GPUs and two 1GB frame buffers on a single card. That’s enough to wipe the floor with any single-GPU solution Nvidia has yet fielded. And you can put two of those beasts in a CrossFire rig and harness the power of four GPUs.

So which videocard is right for your needs? Our buyers guide will help you decide.

Multi-GPU Support

If you want the ultimate in gaming performance, build your next PC (or upgrade your existing machine, if it’s compatible) so that you can tap the power of more than one videocard. AMD calls its solution CrossFire and Nvidia pitches its as SLI (Scalable Link Interface). Not all motherboards are capable of supporting more than one videocard, so check your documentation before you buy anything. AMD is slightly more permissive with CrossFire than Nvidia is with its SLI solution: Many Intel chipsets support AMD’s solution; relatively few are compatible with SLI. Refer to the section on motherboards for more details.

As noted above, however, you don’t necessarily need two videocards to get dual-GPU performance. AMD’s Radeon 4870 X2 mounts two of that company’s best GPUs (and two matching frame buffers) on a single card to deliver a product that’s faster than any single GPU Nvidia currently has to offer—and it doesn’t matter which chipset you run it on. Nvidia offers a dual-GPU configuration on a single card, too (the GeForce 9800 GX2), but it doesn’t have such an animal based on its newest GPU, the GeForce 280 GTX.

DirectX 10 Support

DirectX is a collection of APIs that Microsoft developed to make it easier for game developers to program for the latest PC hardware. DirectX 10, of which Shader Model 4.0 is a part, is supported on all Nvidia videocards beginning with the GeForce 8 series and on all AMD videocards beginning with the Radeon 2000 series. In other words, just about any card you might be considering upgrading to supports these important graphics standards.

AMD’s Radeon HD 3000- and 4000-series cards also support the most recent “point release” in DirectX technology: DirectX 10.1 and Shader Model 4.1. AMD gains little from this, however, because game developers have barely tapped what’s possible with DirectX 10 and have shown little interest in moving on to the incremental releases. What’s more, DirectX 10 is available only on the Vista operating system; if you’re still rolling with Windows XP, DX10 support is totally irrelevant.

DisplayPort, HDMI, and HDCP

DisplayPort and HDMI are both standards for connecting your videocard to a digital display; HDCP is a copy-protection scheme developed for high-definition movies. None of these is critical to gaming, unless you intend to connect your PC to a big-screen TV that doesn’t have a DVI port (an older type of digital-video connection).

Since most people—even hard-core gamers—use their PCs for more than just gaming, we think HDCP support is an important feature. You’ll need it if you ever want to watch a Blu-ray movie on your PC. Be aware that many cards offer HDMI via an adapter that plugs into a DVI port on the back of the card. This will add a couple of inches to your PC’s overall footprint, which can be a problem if you’re squeezing the box into an entertainment center. An HDMI port directly on the mounting bracket is a far superior solution, but surprisingly few cards offer this feature.

Frame Buffer

When it comes to memory, more is better if you’re going to play the most demanding new games at high resolutions. Even low-end cards come with 256MB, and higher-end cards come with 512MB or even 1GB onboard.
The type of memory is less important: Nvidia continues to use GDDR3, while AMD has moved on to GDDR4 and GDDR5 for many of its products.

Physics Acceleration

Anyone who’s played Half-Life 2—and that’s just about everyone—knows how much fun real-time physics can add to a game. Intel certainly knows: The company snapped up physics middleware developer Havok in 2007.

AMD and Nvidia would like to see physics code running on the GPU, not the CPU. The two companies have blown an awful lot of hot air on this topic in the past two years but have little to show for it. Ageia, the only company to have developed a dedicated physics co-processor—the PhysX PPU—failed to gain any market share at all. Nvidia bought the flailing company earlier this year, but no one was surprised when Nvidia announced they were interested only in Ageia’s PhysX API—the PhysX coprocessor is officially kaput.

Theoretically, the PhysX software should be able to run on any processor—be it a CPU, GPU, or PPU, but Nvidia could decide to restrict PhysX acceleration to its own products. It’s all academic at this point. Until we encounter a great game that makes outstanding use of PhysX, we see little reason to recommend the technology over Havok or anything else. 

The Ageia-powered Unreal Tournament III Tornado mod featured a whirling vortex that tears the battlefield apart as the game progresses. The tornado could also suck in projectile weapons, such as rockets, adding an exciting new dynamic to the game.

Unfortunately for Ageia, mods such as this were too few and far between, and this chicken-or-the-egg conundrum ultimately killed the PhysX physics processing unit. By the time Nvidia acquired the company, Ageia had convinced just two manufacturers—Asus and BFG—to build add-in boards based on the PPU, and Dell was the only major notebook manufacturer to offer machines featuring the mobile version. Absent a large installed base of customers, few major game developers (aside from Epic and Ubisoft’s GRAW team) saw any reason to support the hardware.

Nvidia has a much more persuasive argument: Effective with the release of its GeForce driver version 177.92, every videocard with a GeForce 8-, 9-, or GTX 200-series processor and 256MB of memory is capable of accelerating PhysX routines. That’s an installed base of 90 million units—a number Nvidia expects to swell to 100 million by the end of 2008.
Even then, we predict PhysX will need a killer app if it’s to really take off. Nvidia will need to help foster the development of more PhysX-exclusive games, such as the Tornado and Lighthouse mods for Unreal Tournament 3, and the Ageia Island level in Ghost Recon: Advanced Warfighter.

Nvidia will also remedy one of Ageia’s key marketing mistakes: Consumers couldn’t run a PhysX application unless they had a PhysX processor, which meant they had no idea what they might be missing out on. Under Nvidia’s wing, PhysX applications will fall back to the host CPU in the absence of a CUDA-compatible processor. The app might run like a fly dipped in molasses, but if gamers with PhysX cards boast of a killer gaming experience, it could fuel demand for PhysX-capable videocards. At the very least, it enables Nvidia to claim a diffrentiating feature against AMD. 

Should You Do the Multi-GPU Tango?

A rig with two GPUs should render graphics twice as fast as an otherwise identical machine outfitted with just one videocard, right? Well, not necessarily. In fact, you can drop three Nvidia GPUs in a rig or four AMD graphics processors in the same box and still not see an appreciable performance boost with some games.

In many situations, a custom profile must be added to the videocard’s driver before a game will recognize and assign part of its rendering workload to second and subsequent GPUs. And even that might not be enough to make an appreciable difference in performance with games like Crysis when you crank up anti-aliasing and anisotropic filtering, because the GPUs might be left starved for memory.

Dropping two videocards with 512MB frame buffers each in a machine doesn’t suddenly endow that rig with a 1GB frame buffer; each videocard’s frame buffer is segregated. The same goes for videocards that have two GPUs onboard, such as the AMD Radeon HD 4870 X2. That card has a whopping 2GB of GDDR5 video memory onboard, but it’s divided into two discrete 1GB frame buffers; each GPU is limited to addressing 1GB of memory.

Moving beyond one modern Nvidia GPU or two modern AMD GPUs will also require a motherboard that supports the feature. Although things are getting better on that front with the launch of Intel’s Core i7 (boards with Intel’s X58 chipset will support both Nvidia’s SLI and AMD’s CrossFire architectures), current LGA775 motherboards can support only one or the other—and Socket AM2 motherboards support only CrossFire.