AMD CrossFireX

Description 

·         Theoretically, the same GPU to GPU involving 2 × 2 increase performance. But in practice it is around 1.7-2 ×, when certain measurements, the resulting output more than doubled, but it is only for specific cases. When connecting more than 2 GPU is already smaller increase in performance. U 3 GPU that's about 250% 1 GPU. U 4 GPU performance increase is only SW that has it written support, otherwise the performance make about the involvement of 2 or 3 GPU.

·         At lower resolution may not be GPU performance increase 2 to 1 GPU noticeable. Therefore, involvement of two or more GPUs only recommended in full HD (1920x1080) and higher, while smoothing power (AA), and high-quality effect.

·         Under certain circumstances may occur in poor performance when connecting CF vs 1 GPU, it usually occurs in non-optimized game engines for multiple GPU.

·         Putting DirectX 11 slightly improved using multiple GPU support each other and improve performance, but still need optimization by game developers and driver developers.

·         CrossFireX can connect up to four graphics chips, so it involved one-chip card + 1-chip card, smart card-1 + 2-chip card, 4 × 1-chip card or a 2 × 2-chip card. The biggest performance gains can be recognized between one and two kartama, then in most applications, the performance rises up it was only a few tens of percent.

·         When using AFR may experience an issue where the image is slightly uncomfortable lugs, without influence on the course of FPS (so-called micro stuttering ).

·         To determine the active CF uses a specific algorithm, which is described in the documentation of AMD. The algorithm varies according to the needs of AMD as it
      develops hardware and software (VISION Engine Control Center).

·         AMD to design series GPU Radeon R900 more thought to use a CF because some GPU gives better performance compared to their predecessors.

Generation 

The first generation 

CrossFire was first released to the public on the 27th September 2005 . Technology called CrossFire compatible motherboard with a pair of ATI Radeon connected via PCI-Express (PCIe). Radeon X800, X850, X1800 and X1900 were published in two editions, in classical and CrossFire. CrossFire Edition is characterized by the "Master" built directly into the hardware card. As a "Master" is called with five integrated circuits for image composition , which helped to combine the outputs of both cards. Therefore enough to buy one "Master" card and pair of her classic of the same series. "Master Card" is supplied with a special DVI combiner (the so-called Y-Dongle), which combined the two main video outputs of both card into one input on the monitor . The combiner served as the main liaison between the cards that sent incomplete images and combining them into one complete monitor. Low-end Radeon X1300 and X1600 CrossFire Edition had, but it was CrossFire compatible with software that communicates over a standard PCI-Express slot. ATI has not yet infrastructure to enable CrossFire on their FireGL cards. "Slave" card must be the same model as the "Master".

Graphics Card X850 chip using Silicon Image (SiI 163B TMDS), which had limited the frequency resolution of 1600 × 1200 at 60 Hz or 1920 × 1440 at 52 Hz, due to this problem was applicable only to CRT 1280x1024 resolution, because not so interested in CF, price exceeded usability.

The second generation (Software CrossFire) 

When using the chipset CrossFire Xpress 3200 from ATI has no need of "Master" for all CrossFire compatible card (only exception being the Radeon X1900 series). With CrossFire Xpress 3200classic to two cards in CrossFire work, communication mediated through the PCI-Express slot . This is similar as in the communication card X1300, except that Xpress 3200 was specifically designed for low response and high-speed communications between the graphics card. Increased performance and eliminating the "Master" was considered an overall improvement in market strategy of the company as "Master" cards were very expensive, demand exceeded supply, and it is possible to get only at selected retailers. Although the CrossFire Xpress 3200 really lets you take advantage of CrossFire through the PCI-Express for each lower than the Radeon X1900, Radeon X1800 drivers have not yet been assembled. ATI said that support for the Radeon X1800 will be released along with their Catalyst driver, but the date was never specified.

X1800 graphics card using 2 chips Silicon Image (SiI 163B TMDS), because it was not limited to that of the first generation of the frequency and resolution.

The current generation (CrossFireX) 

Sample diagram with two CrossFire Radeon 4850 ( Radeon R700 GPU)

With the release of the Radeon X1950 series, ATI completely revised interconnection infrastructure CrossFire connectors eliminate the need for a division of the "Master" and "Slave" functionality for CrossFire technology. ATI CrossFire connector is now "more they were" attached to the side of each card, as is the case with the same technology SLI competitor nVidia , only with other physical and logical features. Thanks to cease "Master" card the highest performance, and therefore ceased to exist. Series cards Radeon HD 2900 and HD 3000 are two identical "braces" connectors, but the HD 3800 series requires only one connector, which makes it easier to connect CrossFireX. Unlike older series, card series Radeon HD 3800 may not be the same model (but of the same series should be), and can be connected via CrossFire, while controlling stroke each card separately.

19th July 2007 issued by AMD (which a year ago bought ATI Technologies) marked a new desktop platform codenamed Spider . CrossFire was subsequently updated to support up to four cards, disposing 790FX chipset, connected at the same time. Thanks to this designation was changed to CrossFire ATI CrossFireX. Involvement of four graphics cards in CrossFire, as referenced AMD internal testing should provide an increase in performance of up to 320% in many games and applications that require large graphics computing capabilities. This however is due to high cost focusing only on the market for real enthusiasts. Recent developments in CrossFire infrastructure includes support for cards with two GPU cores, which were issued in early2008 , the models Radeon HD 3870 X2 and younger Radeon HD 4870 X2 , which contain only one CrossFire connector, but thanks to the installation of 2 GPU and so achieves a performance of "four" cards.

Catalyst 11.1 and later supports CrossFire profiles, the AMD issue as soon as possible after the new games for maximum performance CF in the game.

The GPU R900 can have efficiency diagram 2 GPU to 200% power 1 GPU, because in some tests came over SLI performance.

Hybrid CrossFireX 

Hybrid CFX support only some chipsets with IGP . Allow you to work IGP with dedicated graphics card. Power it will only increase the involvement of the lowest class of dedicated graphics cards due to poor performance IGP.

Supported chipsets are the 700 and 800 known as Hybrid CrossFire X.