UPDATE: Benchmark results of 3-way ATI CrossFire added.
The concept of a top-performance multi-processor graphics subsystem is one of those ideas that get completely forgotten only to emerge again after a while. 3dfx’ SLI, ATI’s Rage Fury MAXX, S3’s MultiChrome were just a few attempts to realize that concept. Some of them were successful, some were a complete failure like the XGI Volari Duo, but the evolution of multi-GPU solutions eventually gave birth to two viable technologies, ATI CrossFire and Nvidia SLI, which took a small, yet stable, niche on the market of top-class gaming systems.
As we have repeatedly written in our reviews, multi-GPU technologies could not take root in the inexpensive solutions sector. It is generally better to buy one top-end card instead of two mainstream ones. One of the reasons is the specifics of today’s game engines (HDR, complex shaders with loops, branches and dependencies, multiple-pass or deferred rendering, post-processing, etc) that don’t allow getting the highest performance from multi-GPU systems without application-specific software optimizations. But the user doesn’t want to know anything about these difficulties. He wants the graphics card he has bought to deliver its maximum performance in every game. And that’s something that today’s multi-GPU solutions can’t offer. Consequently, they can’t avoid the status of an “expensive toy for enthusiasts”. Well, the most popular games do get the necessary optimizations quickly, which is an additional factor that keeps multi-GPU technologies afloat. There is another factor, though: speed. For those who do not mind the price or stability concerns.
Sometimes the performance of GPUs doesn’t grow up fast enough to keep up with system requirements of newest games. We can recall Crysis that cannot run at an acceptable speed in any of contemporary systems if you select the highest level of detail in it. Creating a new GPU is a complex, long and expensive process, and there can be periods when the GPU developer doesn’t have a graphics core with sufficient performance just at the moment. On the other hand, the current market of 3D graphics forgives no delays. If you delay today, you will suffer huge losses or will even have to leave the market altogether tomorrow. The developers have to find ways to maintain the performance growth and win some time. That’s when the multi-GPU concept comes in handy. As you know, the graphics department of Advanced Micro Devices, the former ATI Technologies, did not have a graphics core capable of matching Nvidia’s G92 and had to resort to CrossFire technology, creating the ATI Radeon HD 3870 X2 graphics card with two RV670 chips on board. Our tests showed that the card had a serious potential. Even though it did not win all the tests, the ATI Radeon HD 3870 X2 became the fastest single graphics card available, allowing ATI to claim technological superiority after a long while.
The competition on the consumer 3D graphics market never ends, though. And Nvidia has introduced a new solution to knock the Radeon HD 3870 X2 off the throne. Not having a new-generation graphics core right now, the company followed the same route as ATI when creating its new GeForce 9800 GX2. After all, Nvidia had already had an experience developing dual-processor graphics cards.