Original URL: http://www.theregister.co.uk/2005/05/06/ati_mvp_details/
ATI multi-card rendering details emerge
Turns to tiles - but where's the grouting?
ATI's SLi-style multi-card image rendering system will be able to use any of the company's 3D graphics cards, if claims made by hardware website Hexus.net are anything to go by.
ATI's system - apparently dubbed Multi Video Processing (MVP) - will, like Nvidia's rival SLi technique, speed image rendering by getting two GPUs to co-operatively render each 3D scene.
Citing a number of sources, the site claims  ATI's approach uses a master/slave system. The slave card can be any ATI board - only the master card needs to specifically support MVP. Nvidia's alternative requires two SLi-compatible boards to be used.
MVP was previously believed to operate across the PCI Express bus, avoiding the need for the proprietary card-to-card connector used by Nvidia's SLi boards. However, the sources claim ATI's system actually connects the two boards via a backplane connection - presumably feeding the slave card's video output into the master card's video-in part. ATI's solution will also require a suitable mobo.
One particularly interesting aspect of Hexus' revelation is ATI's use of a tile-based rendering scheme. Instead of doing the whole scene as one, the image is partitioned into squares, the better to minimise the bandwidth needed to bat a rendered tile from one card to the other.
It's an interesting trick that goes back to the early 1990s when Imagination Technologies was developing its PowerVR line of graphics chips. PowerVR technology was used in Sega's ill-fated Dreamcast, which used a tile-based rendering scheme, as did other PowerVR-based products such as the Kyro range of graphics cards.