There is no question that memory bandwidth limitations are on the minds of every major graphics chip producer. Current generation products reflect the fear that the door is quickly closing on the amount of information that can be passed over a conventional video card's memory bus. ATI was first to tackle the memory bandwidth problem with the introduction of their HyperZ technology, technology which proved to provide up to a 40% performance increase in our tests. Although HyperZ was initially found only in the high end Radeon DDR card, it was not long before subsequent Radeon products carried HyperZ technology into nearly every price range. Just recently we saw NVIDIA take similar bandwidth saving steps with their Lightspeed Memory Architecture in the new GeForce3 card; a technology which will surely find its way into lower costing NVIDIA parts in time. Also in the spotlight in past months was 3dfx's Gigapixel technology which promised to bring memory bandwidth requirements down to a fraction of what they are currently. Naturally, NIVDIA's recent purchase of 3dfx assets leaves Gigapixel technology in the hands of NVIDIA.
With all the bandwidth saving technologies currently out there, the truth of the matter is that the optimizations now in place are not even close to the point that prevents the memory bus from acting as the largest bottleneck. Even the 40% speed boost that HyperZ provided was not enough to get the effective fill rates of video cards (the fill rate of a whole product) any where near the promised theoretical fill rate (fill rates of just the graphics processor alone). It is clear that in future products either these optimizations will have to get drastically better or memory technology get exponentially faster in order for video card performance to keep increasing at the rate it has done in the past.
From a manufacturing perspective, it is impossible to count on new memory technology to save the day. Currently there is nothing out there that can inexpensively increase the memory performance of today's fastest DDR memory chips. Although a new, cheap, fast memory technology could theoretically be discovered tomorrow, one can not base a product on technology that does not yet exist.
At the same time, there is a limitation as to how much bandwidth savings can be implemented in the traditional method of rendering. Often times, even slight decreases in memory bandwidth consumption are very difficult to engineer and put in practice. It is for this reason that many in the video card industry are predicting a change, moving us away from the traditional mode of rendering into one where memory bandwidth savings are paramount.
Spearheading the move away from conventional rendering has been Imagination Technology. For years now Imagination has predicted the memory bandwidth crunch that appears to have recently hit home with every major video card manufacturer. Continuing their trend away from conventional rendering paradigms, today STMicroelectronics releases Imagination's latest stab at tile based rendering, this time initially sold under the Hercules name of video cards. Called the Kyro II and promising high-end performance at a fraction of the price, let's see if the latest generation of tile base rendering can outperform an extremely aged rendering platform.