Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
ATI CrossFire

ATI CrossFire

Discussion
Ask a question about 'ATI CrossFire'
Start a new discussion about 'ATI CrossFire'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia
AMD CrossFireX is a brand name for the multi-GPU
Graphics processing unit
A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...

 solution by Advanced Micro Devices
Advanced Micro Devices
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...

, originally developed by ATI Technologies
ATI Technologies
ATI Technologies Inc. was a semiconductor technology corporation based in Markham, Ontario, Canada, that specialized in the development of graphics processing units and chipsets. Founded in 1985 as Array Technologies Inc., the company was listed publicly in 1993 and was acquired by Advanced Micro...

. The technology allows up to four GPUs to be used in a single computer to improve graphics performance.

First-generation


CrossFire was first made available to the public on September 27, 2005. The system required a CrossFire-compliant motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

 with a pair of ATI Radeon
Radeon
Radeon is a brand of graphics processing units and random access memory produced by Advanced Micro Devices , first launched in 2000 by ATI Technologies, which was acquired by AMD in 2006. Radeon is the successor to the Rage line. There are four different groups, which can be differentiated by...

 PCI Express
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

 (PCIe) graphics cards. Radeon x800s
Radeon R420
The Radeon R420 core from ATI Technologies was the company's basis for its 3rd-generation DirectX 9.0/OpenGL 2.0-capable graphics cards. Used first on the Radeon X800, R420 was produced on a 0.13 micrometer low-K process and used GDDR-3 memory...

, x850s, x1800s and x1900s came in a regular edition, and a 'CrossFire Edition' which has 'master' capability built into the hardware. 'Master' capability is a term used for 5 extra image compositing chips, which combine the output of both cards. One had to buy a Master card, and pair it with a regular card from the same series. The Master card shipped with a proprietary DVI
Digital Visual Interface
The Digital Visual Interface is a video interface standard covering the transmission of video between a source device and a display device. The DVI standard has achieved widespread acceptance in the PC industry, both in desktop PCs and monitors...

 Y-dongle, which plugged into the primary DVI ports on both cards, and into the monitor
Computer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

 cable. This dongle serves as the main link between both cards, sending incomplete images between them, and complete images to the monitor. Low-end Radeon x1300
Radeon R520
ATI's "R520" core is the foundation for a line of DirectX 9.0c and OpenGL 2.0 3D accelerator X1000 video cards. It is ATI's first major architectural overhaul since the "R300" core and is highly optimized for Shader Model 3.0. The Radeon X1000 series using the core was introduced on October 5,...

 and x1600 cards have no 'CrossFire Edition' but are enabled via software, with communication forwarded via the standard PCI Express
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

 slots on the motherboard. ATI currently has not created the infrastructure to allow FireGL
ATI FireGL
The ATI FireGL range of video cards, renamed to FirePro 3D in late 2008, is the series specifically for CAD and DCC software, usually found in workstations.-History:...

 cards to be set up in a CrossFire configuration. The 'slave' graphics card needed to be from the same family as the 'master'.

An example of a limitation in regard to a Master-card configuration would be the first-generation CrossFire implementation in the Radeon X850 XT Master Card. Because it used a compositing chip from Silicon Image
Silicon Image Inc.
Silicon Image is a provider of wireless and wired connectivity solutions that enable the reliable distribution and presentation of high-definition content for consumer electronics, mobile, and PC markets...

 (SiI 163B TMDS), the maximum resolution on an X850 CrossFire setup was limited to 1600×1200 at 60 Hz, or 1920×1440 at 52 Hz. This was considered a problem for CRT
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...

 owners wishing to use CrossFire to play games at high resolutions, or owners of Widescreen LCD monitors. As many people found a 60 Hz refresh rate with a CRT to strain one's eyes, the practical resolution limit became 1280×1024, which did not push CrossFire enough to justify the cost. The next generation of CrossFire, as employed by the X1800 Master cards, used two sets of compositing chips and a custom double density dual-link DVI Y-dongle to double the bandwidth between cards, raising the maximum resolution and refresh rate to far higher levels.

Second-generation (Software CrossFire)


When used with ATI's "CrossFire Xpress 3200
Xpress 3200
The Xpress 3200 is a new revision of the Xpress 200 computer chipset released by ATI. The chipset supports AMD64 processors of the Socket 939 and also of the Socket AM2.-History of the Xpress 3200 chipset:...

" 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, using the PCI-E
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

 bus for communications. This is similar to X1300 CrossFire, which also uses PCI Express, except that the Xpress 3200 had been built for low-latency and high-speed communication between graphics cards. While performance was impacted, this move was viewed as an overall improvement in market strategy, because Crossfire Master cards were 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 dongle
Dongle
A software protection dongle is a small piece of hardware that plugs into an electrical connector on a computer and serves as an electronic "key" for a piece of software; the program will only run when the dongle is plugged in...

less CrossFire, but has not yet mentioned a specific date.

Current generation (CrossFireX)


With the release of the Radeon
Radeon
Radeon is a brand of graphics processing units and random access memory produced by Advanced Micro Devices , first launched in 2000 by ATI Technologies, which was acquired by AMD in 2006. Radeon is the successor to the Rage line. There are four different groups, which can be differentiated by...

 X1950 Pro (RV570
Radeon R520
ATI's "R520" core is the foundation for a line of DirectX 9.0c and OpenGL 2.0 3D accelerator X1000 video cards. It is ATI's first major architectural overhaul since the "R300" core and is highly optimized for Shader Model 3.0. The Radeon X1000 series using the core was introduced on October 5,...

 GPU), ATI has completely revised CrossFire's connection infrastructure to further eliminate the need for past Y-dongle
Dongle
A software protection dongle is a small piece of hardware that plugs into an electrical connector on a computer and serves as an electronic "key" for a piece of software; the program will only run when the dongle is plugged in...

/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
Scalable Link Interface
Scalable Link Interface is a brand name for a multi-GPU solution developed by NVIDIA for linking two or more video cards together to produce a single output...

 bridges, but different in physical and logical natures. As such, Master Cards no longer exist, and are not required for maximum performance. Two dongles can be used per card; these were put to full use with the release of CrossFireX. Radeon HD 2900 and HD 3000 series cards use the same ribbon connectors, but the HD 3800 series of cards only require one ribbon connector, to facilitate CrossFireX. Unlike older series of Radeon cards, different HD 3800 series cards can be combined in CrossFire, each with separate clock control.

Since the release of the codenamed Spider desktop platform from AMD on November 19, 2007, the CrossFire setup has been updated with support for a maximum of four video cards with the 790FX chipset; the CrossFire branding was then changed to "ATI CrossFireX". The setup, which, according to internal testing by AMD, will bring at least 3.2x performance increase in several games and applications which required massive graphics capabilities of the computer system, is targeted to the enthusiast market.

A later development to the CrossFire infrastructure includes a dual GPU solution with on-board PCI-E bridge that was released in early 2008, the Radeon HD 3870 X2 and later in Radeon HD 4870 X2 graphics cards, featuring only one CrossFire connector for dual card, four GPU scalability.

Hybrid CrossFireX



There is also a “hybrid” mode of CrossFireX which combines on-board graphics using the AMD northbridge
Northbridge (computing)
The northbridge has historically been one of the two chips in the core logic chipset on a PC motherboard, the other being the southbridge. Increasingly these functions have migrated to the CPU chip itself, beginning with memory and graphics controllers. For Intel Sandy Bridge and AMD Fusion...

 architecture with select graphic cards. The current generation is called Hybrid CrossFireX and is available for motherboards with integrated AMD chipsets in the 7
AMD 700 chipset series
The AMD 700 chipset series is a set of chipsets designed by ATI for AMD Phenom processors to be sold under the AMD brand...

 and 8
AMD 800 chipset series
The AMD 800 chipset series is a set of chipsets developed by AMD, released in 2009. The chipset series was revealed in its presentation slides during the AMD Financial Analyst Day 2007 held on December 13, 2007...

 series IGPs, referred to as Hybrid CrossFire X. It allows combining discrete video card(s ) and the IGP for increased performance. This combination results in power-savings when simple or 2D graphics are used and performance increases of 25% to over 200% in 3D graphics over using a non CrossFire option.

Advantages

  • CrossFire can be implemented with varying-GPU cards of the same generation (this is in contrast to Nvidia's SLI, which generally only works if all cards have the same GPU). This allows buyers who have varying budgets over time to purchase different cards and still get the benefits of increased performance. With the latest generation cards, they will only crossfire with other cards in their sub series. For example, GPU in the same series can be crossfired with each other. So a 5800 series GPU (e.g. a 5830) can run together with another 5800 series GPU (e.g. 5870). However GPU's not in the same hundred series cannot be crossfired successfully. (e.g. a 5770 cannot run with a 5870)

  • ATI has opened the CrossFire architecture to Intel, allowing CrossFire to be enabled on many Intel chipset
    Chipset
    A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...

    s which feature two x16 PCI-E slots. SLI
    Scalable Link Interface
    Scalable Link Interface is a brand name for a multi-GPU solution developed by NVIDIA for linking two or more video cards together to produce a single output...

    , however, requires a motherboard
    Motherboard
    In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

     which is SLI certified, which includes all nForce
    NForce
    The nForce is a motherboard chipset created by Nvidia for AMD Athlon and Duron microprocessors. The chipset shipped in 3 varieties; 220, 415, and 420. 220 and 420 are very similar with each having the integrated GPU, but the 220 only has a single channel of memory available whereas 420 has the...

     chipsets (such as the nForce 590 SLI
    NForce 500
    The nForce 500 is a motherboard chipset series and the successor to the nForce4 series. It was revealed by NVIDIA on 2006-03-07 and released on 2006-05-23...

    , nForce 680i SLI
    NForce 600
    The nForce 600 chipset was released in the first half of November 2006, coinciding with the GeForce 8 series launch on November 8, 2006. The nForce 600 supports Intel's LGA 775 socket and AMD's Quad FX platform and replaces the nForce 500 series....

    , and nForce 790i
    NForce 700
    The nForce 700 is a chipset series designed by Nvidia first released in December 2007. The series supports both Intel Core 2 and AMD Phenom processors, and replaces the nForce 600 series chipsets...

    ), and most Intel X58
    Intel X58
    The Intel X58 is an Intel chip designed to connect Intel processors with Intel QuickPath Interconnect interface to peripheral devices. Supported processors implement the Nehalem microarchitecture and therefore have an integrated memory controller , so the X58 does not have a memory interface...

     and Intel P55
    Intel P55
    The Intel P55 is the first desktop chipset from Intel based on the PCH chipset design. The P55 Express chipset uses the LGA 1156 socket. Compatible CPUs include the Core i3, i5, and i7 processor line along with a Pentium Processor G6950...

     based motherboards.

  • ATI crossfire configurations can run many monitors of varying size and resolution, while SLI only allows two monitors. The exception is when Nvidia surround is being used though monitors must be the same resolution for this to work.

Disadvantages

  • If an OpenGL
    OpenGL
    OpenGL is a standard specification defining a cross-language, cross-platform API for writing applications that produce 2D and 3D computer graphics. The interface consists of over 250 different function calls which can be used to draw complex three-dimensional scenes from simple primitives. OpenGL...

     game does not have a CrossFire profile, the Catalyst AI system will set the rendering mode to Scissor by default, with no way to change it to a more suitable or faster mode, such as AFR
    Alternate Frame Rendering
    Alternate Frame Rendering is a technique of graphics rendering in personal computers which combines the work output of two or more graphics processing units for a single monitor, in order to improve image quality, or to accelerate the rendering performance...

    . However, SLI allows the rendering mode to be set for each application manually, even for games which do not have an existing profile. Setting Catalyst AI to 'Advanced' allows manual mode setting for Direct 3D games, but not OpenGL games, to AFR.

Caveats

  • The first generation CrossFire implementations (the Radeon X800 to X1900 series) require an external y-cable/dongle
    Dongle
    A software protection dongle is a small piece of hardware that plugs into an electrical connector on a computer and serves as an electronic "key" for a piece of software; the program will only run when the dongle is plugged in...

     to operate in CrossFire mode due to the PCI-e bus not being able to provide enough bandwidth to run CrossFire without losing a significant amount of performance.
  • In some cases CrossFire doesn't improve 3D performance – in some extreme cases, it can lower the framerate due to the particulars of an application's coding. This is also true for Nvidia's SLI, as the problem is inherent in multi-GPU systems. This is often witnessed when running an application at low resolutions.
  • When using CrossFire with AFR
    Alternate Frame Rendering
    Alternate Frame Rendering is a technique of graphics rendering in personal computers which combines the work output of two or more graphics processing units for a single monitor, in order to improve image quality, or to accelerate the rendering performance...

    , the subjective framerate can often be lower than the framerate reported by benchmarking applications, and may even be poorer than the frame rate of its single-GPU equivalent. This phenomenon is known as micro stuttering
    Micro stuttering
    Micro stuttering is a term used in computing to describe a quality defect inherent to multi-GPU configurations, such as nVidia SLi and AMD CrossFireX, using AFR...

     and also applies to SLI since it's inherent to multi-GPU configurations.

See also

  • Scalable Link Interface
    Scalable Link Interface
    Scalable Link Interface is a brand name for a multi-GPU solution developed by NVIDIA for linking two or more video cards together to produce a single output...

  • MultiChrome
    MultiChrome
    MultiChrome is a technique by S3 Graphics to couple multiple graphics chips for better performance. It has first been used in the Chrome S20 series and later in Chrome 400 series graphics processors...

  • Comparison of ATI chipsets
    Comparison of ATI chipsets
    -Comparison of Northbridges:Note 1: A-Link Express and A-Link Express II is essentially PCI-Express x4 lanes, so that any PCI Express capable southbridge can be used ....

  • Comparison of AMD chipsets
    Comparison of AMD chipsets
    This is a comparison of chipsets sold under the brand AMD, manufactured before May 2004 by the company itself, before the adoption of open platform approach as well as chipsets manufactured by ATI Technologies after July 2006 as the completion of the ATI acquisition.- AMD-xxx :- A-Link Express II...

  • Micro stuttering
    Micro stuttering
    Micro stuttering is a term used in computing to describe a quality defect inherent to multi-GPU configurations, such as nVidia SLi and AMD CrossFireX, using AFR...

  • Hybrid CrossFireX

External links