AMD CrossFireX

AMD CrossFireX (previously known as ATI CrossFireX ) is a multi-GPU technology company AMD. The technology allows the user up to four AMD Radeon graphics cards to operate in a PCI Express system at the same time to increase the graphics performance. In addition, this technology is used in dual-GPU graphics cards and systems ( in the chipset or CPU chip ) integrated GPU are combined by means of this technique with an additional graphics card under the marketing term " Radeon Dual Graphics". Based on ATI CrossFireX multi- rendering technology and brought this technology to the mass market.

Operation

After introduction of the CrossFire technology is a proprietary video cable ( DVI Y- dongle) still needed, over which both graphics cards are connected externally to the DVI port, so there can be a data exchange between the video cards. Here is a so-called master card is required ( the name " Crossfire Edition" recognizable), with a slave card ( standard version ) is combined. A chip on the master card controls the data exchange between the two graphics cards to output an image on the monitor can.

The end of 2006, with the introduction of the Radeon X1650 XT and Radeon X1950 Pro was the internal Crossfire, referred to by AMD as " native", presented. About two ports, two identical graphics cards are connected to a Crossfire bridge cable. The monitor is connected to one of the two video cards. The exceptions are the low-end or some mainstream graphics cards that require less bandwidth than the performance and high-end graphics cards. Here, the communication between the two graphics cards made ​​exclusively via the PCI Express bus, similar to MultiChrome of S3 Graphics.

The end of 2007 was introduced with AMD's Spider Platform CrossFireX. With CrossFireX it is now possible to operate up to four GPUs simultaneously. The difference with SLI from NVIDIA is that when Crossfire data can be exchanged bidirectionally in general.

End of 2013, AMD has announced the introduction of the graphics cards codenamed Hawaii for the first time the so-called XDMA technology. By " XDMA " (X = Crossfire, DMA = Direct Memory Access) it should be possible to dispense even with high-end graphics cards on the additional bridges between the graphics card and leave the communication between the GPUs run over PCIe.

Differences in the Crossfire generations

Mikroruckler

Both Crossfire and SLI set mainly on Alternate Frame Rendering. Here, there is currently often the phenomenon in that each second frame is calculated slower than the previous one. It comes to so-called " micro stuttering ". This leads to an uneven flow of the game, which is annoying especially at relatively low frame rates. This circumstance graphics cards need in CrossFire mode in the matches in question, a significantly higher average frame rate than a single graphics card to ensure a relatively smooth representation to the eye. This problem also occurs when dual-GPU graphics cards, as well as in " Dual Graphics " systems, since both also draws on the CrossFire technology. The fact that the higher average FPS do NOT provide better playability in benchmarks in CrossFire mode, means that in detailed test reports, particularly of discouraged with CrossfireX graphics cards to the mainstream and a single card is recommended.

In August 2013, AMD has implemented the so-called frame - pacing in the Catalyst 13.8 Beta 1 driver. Here, the very fast frame calculated at the output to the screen by an intermediate buffers is slightly delayed. The frame rates are thus again more evenly and the maximum latency between two consecutive frames are smaller, because the waiting time is reduced to the following, slowly calculated frame. By this workaround occur significantly less Microruckler and the games will play better, even if the average FPS number drops slightly. The improvements are almost everywhere palpable and the result is just as good as with SLI systems where this technique is used for some time. Thus the Microruckler are not completely gone, but the flow of the game is now for the first time with the single- GPU systems comparable. The first WHQL driver with frame pacing and further improvements AMD has announced for the year 2014. Currently, there are limitations that the frame pacing can be applied only at GPUs with GCN architecture (from HD7000 series) and only up to a resolution of 2,560 × 1,600. Higher resolutions are currently only compatible with Radeon R9 290 and R9 290X with the frame pacing driver. For DirectX 9c and OpenGL games there is also no support for the frame pacing.

Modes of operation

It offered four different operating modes:

  • SuperTiling: Standard for Direct3D applications.
  • Scissor: (also known as Split Frame Rendering (SFR ) with " load balancing "). Standard for OpenGL applications.
  • Alternate Frame Rendering (AFR ): Highest results in benchmarks, but problems with micro stuttering.
  • SuperAA: A quality mode in which both graphics cards charge the same frame with different FSAA pattern. For more FSAA factors are possible.

Graphics cards with Crossfire support

Dual-GPU graphics cards

All previous dual-GPU graphics cards under the brand name based on the ATI CrossFire technology. First made ​​some ATI partners - such as Sapphire or GeCube - under own initiative dual-GPU graphics cards, such as the X1950 Pro X1650 XT Gemini or Gemini. Later, AMD took the reins of the development and all partners presented a reference design before. The two GPUs are connected to the card with a PCIe switch and run in Crossfire mode. Until the HD3870 X2 supported the PCIe PCIe switch the first generation, from HD48xx X2 supports the PCIe switch PCIe 2.0, thus providing more bandwidth for the communication between the two GPUs.

Hybrid CrossFireX

Hybrid CrossFireX It is possible an AMD chipset with Integrated Graphics Processor (from the AMD 7-series chipset series) and a low-end graphics card HD 3450 or HD 3470 (April 2011) to increase interconnect the graphics performance.

The monitor can be connected to the video output to either the motherboard or the discrete graphics card. When connecting the monitor to the motherboard, the graphics card has no function in 2D applications, but it will not shut down. If the monitor is connected to the graphics card in 2D mode only the dedicated graphics card is responsible for the image output, here the IGP is completely switched off. In both cases, the IGP and dedicated graphics card be connected together to increase performance if the Catalyst driver CrossFireX support for each 3D application provides. For non- drive side CrossFireX support 3D applications, it is recommended the monitor to the discrete graphics card to connect because the integrated GPU chipset is less powerful than a Hybrid CrossFireX-ready graphics card.

In Hybrid Crossfire mode, both the integrated on the motherboard GPU and discrete graphics card to render their images independently ( Alternate Frame Rendering ). With the release of the Catalyst Software Suite 8.8 for both Windows XP and Vista are supported.

With the feature " GeForce Boost" Nvidia offers a similar function as hybrid CrossFireX.

A feature similar to Nvidia's " Hybrid Power " which can disable as necessary the discrete graphics card, AMD offers only for notebook chipsets under the name Power Xpress. Power Xpress is currently (as of June 2008) only supported on Windows Vista.

ATI Multi-Rendering Bidirectional (disambiguation) AMD Radeon Rx 200 Series WHQL Testing Pattern (disambiguation) R400 Series R600 (ASIC) Radeon HD 3000 Series Radeon R700 Evergreen (GPU family) Radeon HD 6000 Series Radeon HD 7000 Series ATI Technologies ATI Rage ATI FireMV ATI FireGL Xpress 200 Adreno Xilleon HyperMemory ATI Avivo X-Video Bitstream Acceleration Mantle (API)
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