Is more really better?

AMD is making multi-GPUs its absolute solution for high-end gamers. Our WinLabs editor examines the pros and cons of this approach...

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By  Jason Saundalkar Published  December 5, 2007

On a recent AMD trip to Poland, I had the chance to sit down with Richard Huddy of AMD. Most of our conversation was about his company's new line of graphics cards and CrossFireX technology.

Interestingly, AMD's approach will now be to focus on multiple GPUs as a top-end solution, whereas nVidia is focusing on monolithic, ultra-high-end GPUs as well as its SLI (Scalable Link Interface) multi-GPU technology. There are, as you'd expect, pros and cons to AMD's multi-GPU only approach, so let's examine what these are...

Starting with the positives, the biggest advantage of AMD's approach is that it is flexible. You can start with one or perhaps two of AMD's Radeon HD 3870 cards and, when you want more horsepower, you can combine up to four on high-end Spider-compatible motherboards. On its own, AMD's fastest GPU, the 3870, isn't as fast as nVidia's mid-range GeForce 8800GT, but combining two, three or even four 3870s will give nVidia's a run for its money.

Of course, you're probably thinking that going with four of AMD's best GPUs is going to cost you an arm, a leg and maybe your house but as these GPUs aren't high-end parts - compared to a GeForce 8800 Ultra say - AMD has priced them sensibly. The Radeon HD 3870 for instance should cost no more than $230 on its own, so four would cost $920. By comparison a single GeForce 8800 Ultra will set you back $700. So depending on how much cash you have to spare, you can start off slow and spend more later to turn your rig into an absolute beast.

In terms of scalability, AMD is very keen on getting this right, which makes perfect sense given it is turning to multi-GPU as its best top-end solution. Mr Huddy was adamant that the drivers will be fine tuned to death and expects CrossFireX to provide anywhere between a 65% and 85% improvement in performance. For the last couple of years using either SLI or CrossFire, those sort of improvements were few and far between; performance improvements were generally around the 40% mark.

Previously then multi-GPU was more of a marketing gimmick so it'll be great to have the technology delivering on its promises. And you can be sure that if AMD's CrossFireX does provide those sort of improvements, nVidia will feel the need to get its own SLI tech up to scratch. Competition is a wonderful thing.

Another positive aspect of AMD's multi-GPU approach, although this is probably more of a ‘pro' for the company itself, is that it should now be easier to bang out new GPUs. You see, designing a single ultra-high-end GPU, such as the 8800 Ultra, is difficult and expensive because of the complexities involved with cramming that much power into something the size of a coin. AMD on the other hand doesn't have to worry about producing a single monster GPU, which could mean faster development cycles. This in turn means more choice for consumers and, more importantly, lower prices.

As clever as AMD's approach is however, there are pitfalls. Imagine if you will that you've invested in a high-end Spider-based PC with four 3870 GPUs. Eventually, software will bring these GPUs to their knees, which means you'll need to upgrade. Considering you've got four like GPUs, this means you'll have to bin them and start from scratch. Depending on how often you upgrade your PC then, this route could be quite expensive. If however you switch all four GPUs every two years, the cost should balance out nicely against a single, monolithic ultra-high-end GPU.

The next issue is that for multi-GPU to work, both graphics drivers and your software need to be in tip-top condition. Coding drivers for a single card is tough enough but it becomes even more complex when you have to code drivers for a multi-GPU system. The software you're running should also have a scalable graphics engine because regardless of how good the drivers are, having the actual software ready for multiple GPUs will help its performance.

Overall, I think AMD's approach has merit whether you're an average gamer or a framerate-craving hardcore type. I would just advise that you be aware of its upgrade cycle, lest your made of money.

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