ATI CrossFire

CrossFire was first made available to the public on September 27, 2005.^[1]

The system requires a CrossFire-compliant motherboard with a pair of PCI Express (PCIe) graphics cards, which can be enabled via either hardware or software. Radeon x800s, x850s, x1800s and x1900s come in a 'CrossFire Edition' that has 'master' capability built into the hardware. One must buy a Master card, and pair it with a normal card from the same series. Radeon x1300s and x1600s have no 'CrossFire Edition' but are enabled via software. ATI currently has not created the infrastructure to allow FireGL cards to be set up in a CrossFire configuration. Another point to note is that the 'slave' graphics card needs to be from the same family as the 'master', regardless of whether the 'master' is designated by the hardware or by software.

An example of a past limitation in regard to a Master-card configuration would be the CrossFire implementation in the Radeon X850 XT Master Card using a compositing chip from Silicon Image (SiI 163B TMDS) which limits a X850 CrossFire setup to a resolution of 1600×1200 @60 Hz or 1920×1440 @52 Hz and was a problem for some CRT owners wishing to use CrossFire to play games at high resolutions. As many people would find a 60 Hz refresh rate with a CRT to strain ones eyes, the practical limit becomes 1280×1024, which did not push CrossFire enough to justify the cost.

However, with ATI's release of "CrossFire Xpress 3200" motherboard chipset, the 'master' card is no longer required for every "CrossFire Ready" card (with the exception of the Radeon X1900 series). With the CrossFire Xpress 3200, two normal cards can be run in a Crossfire setup. This move is viewed as an overall improvement in market strategy due to the fact that Crossfire Master cards are expensive, in very high demand, and largely unavailable at the retail level.

Although the CrossFire Xpress 3200 chipset is indeed capable of CrossFire through the PCI-e bus for every Radeon series below the X1900s, the driver accommodations for this CrossFire method has not yet materialized for the X1800 series. ATI has said that future revisions of the Catalyst driver suite will contain what is required for X1800 dongleless CrossFire, but has not yet mentioned a specific date.

With the release of the Radeon X1950 Pro (RV570 GPU), ATI has revised CrossFire's connection infrastructure to further eliminate the need for past Y-dongle/Master card and slave card configurations for CrossFire to operate. ATI's CrossFire connector is now a ribbon like connector attached to the top of each graphics adapter, similar to nVidia's SLi bridges, but different in physical and logical natures.

Since the release of the codenamed Spider desktop platform from AMD on November 19, 2007, the CrossFire setup sees update with the maximum four video card support with the 790FX chipset, the CrossFire branding was then changed to "ATI CrossFire X". The setup, according to AMD's internal testing, will bring at least 3.2x performance increase in several games and applications which required massive graphics capabilities of the computer system, the setup is targeted to the enthusiast market. Later developments include a dual GPU solution to be released early 2008, the "ATI Radeon HD 3870 X2", featuring a CrossFire bridge directly included on the PCB circuitry, with one CrossFire connector for dual card, four GPU scalability. MSI and AMD have acknowledged that the Radeon HD 3870 X2 will support four card CrossFire, to reach octagonal GPU scalability.

Source : wikipedia