Usually, when we're putting together an article like this one, it has an overriding theme. Either we're reviewing a particular video card, or we're conducting a comparative review of similar products. We do have elements of the latter in this article, but we don't have a single, underlying theme other than this: like high-school seniors in summer camp, the graphics cards in question here have paired up. We have CrossFire setups for the latest Radeons, including the HD 6850 and 6870, and we have SLI configs for the latest GeForces, including the brand-spanking-new GeForce GTX 580.
If that's not a coherent enough theme for you, well, our apologies. We've watched too much cable TV to make sense consistently any more. We simply had a few questions we wanted to see answered in the wake of our GeForce GTX 580 review. We wanted to know how that card performs in SLI, because after all, the fastest single GPU money can buy has tremendous potential as a building block of a multi-GPU setup. We also wondered whether a pair of relatively inexpensive video cards, like the Radeon HD 6850 or the GeForce GTX 460 768MB, might not be a viable alternative to a single high-end card like the GTX 580. In order to make sense of those comparisons, we were itching to do one of our patented value analyses on the various single- and multi-GPU offerings.
Undaunted by the multi-faceted nature of our task, we gathered up a bundle of intriguing new video cards and set to testing. We've included everything from a single Radeon HD 6850 to dual GeForce GTX 580s in SLI, along with many notable configs in between, for a total of 16 different combinations. The result is, for better or worse, what you'll see below and on the following pages. Perhaps it will clarify some things for you, in spite of our best efforts.
Some new cards in the deck
In order to answer the questions we posed above, we naturally had to add some new video cards to our stable. That included, of course, a pair of GeForce GTX 580s.
We decided to go asymmetrical for our GTX 580 SLI config, kinda like the chick I dated in high school who had different colored eyes.
The first card in the pair comes from Zotac, and it's a nicely bestickered version of Nvidia's reference design, right down to the GTX 580's standard core and memory clock speeds. This card is currently selling for $529.99 on Newegg, or 30 bucks over Nvidia's suggested e-tail price, as are many other GTX 580 cards. Zotac covers its GTX 580 with a two-year warranty by default, but the term extends to "lifetime" if you register. Beyond that, this card's primary distinguishing feature is a bundled copy of Prince of Persia: The Forgotten Sands. We've not yet played the game, but it has a semi-decent 75 rating on Metacritic, along with a less promising user score of 5.3. Still, the bundled game might be worthy of note, since otherwise, most GTX 580 cards are essentially the same.
Not that there's anything wrong with that. In fact, we quite like the GTX 580 reference design, and we've found Nvidia's stock cooler to be relatively quiet and effective.
Our second GTX 580 card comes from Asus, whose approach to the whole branding thing involves admirable restraint. You'll find no atomic frogs or rocket-propelled fairy godmothers with magic swords on the Asus card itself, just a spare, bold sticker bearing the card maker's name. Under the hood, though, this GTX 580 has been tweaked slightly: the core clock is 782MHz, up 10 whole megahertz from Nvidia's default. In spite of the extra juice, Asus' GTX 580 is going for $524.99 at Newegg, five bucks less than the Zotac, though without the bundled game. Asus covers its video cards with a three-year warranty, and happily, no registration is required to get the full warranty term.
Together, these wonder twins make a slightly asymmetrical $1054.98 graphics powerhouse. By rights, we should have tested this monster SLI setup against a similarly beastly config from AMD involving a pair of Radeon HD 5970 cards. However, we opted to test a pair of Radeon HD 5870s instead, as a sort of consolation prize, for various reasonsmainly because AMD is achingly close to rolling out its brand-new 6900-series GPUs, and we'll be testing those shortly. Those will surely be the GTX 580's real competition.
Ever since we published our review of the Radeon HD 6800 series, we've been hearing from a certain segment of the AMD fan base who desperately wants us to test a version of the Radeon HD 6850 that runs at higher clock speeds than AMD's defaults. That's only fair, they reason, since we also tested some of the many GeForce GTX 460 cards that run at higher-than-base clock frequencies. We were determined to accommodate these requests, a task we found was easier said than done. The Radeon HD 6850 has apparently been quite the hot product, as evidenced by rising prices and spotty availability.
Fortunately, Asus stepped in with a pair of its EAH6850 DirectCU cards for us to test. These have a 790MHz GPU core clock15MHz higher than stockand are presently listed for $199.99 at Newegg. That's not a huge bump in clock speed, but it's about par for the course among Radeon HD 6850s. You will find a few with 820MHz core clocks, but those run $10-20 more than the Asus model we've testedand all are quite a bit above AMD's original $179 suggested price.
At its initial suggested price, the Radeon HD 6850 was set to do battle against the 768MB version of the GeForce GTX 460. However, as the Radeon's price has risen, the GTX 460 768MB's price has remained steady at $169.99. The Asus card in question runs at a 700MHz core clock with 3680 MT/s memory, up from reference speeds of 675MHz and 3600 MT/s. The 6850 is now more direct competition for the 1GB version of the GeForce GTX 460, but we have included the 768MB cards for comparison nonetheless. Both the 6850 and the GTX 460 768MB are intriguing candidates for affordable multi-GPU mayhem, and none is more affordable than this 768MB card.
The Asus 6850 and GTX 460 768MB cards share another attribute, as well: Asus' fancy DirectCU cooler that, per its name, routes a pair of copper heatpipes directly over the surface of the GPU. I don't want to give away too much, but this little innovation may be something more than marketing hype, as we'll soon see.
We should set the table for our testing by reminding you that we've been rather down on the recent trend toward fan-based GPU coolers that don't pipe warm air out directly of an expansion slot opening. Such coolers are typically quiet in single-card configs, but don't fare well when another video card (or any other expansion card) is nestled up against the fan, blocking its airflow. If this Asus cooler performs well in SLI and CrossFire, it will be an exception to the recent trend.
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