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Micro stuttering is a term used in computing to describe a quality defect that manifests as irregular delays between

frames A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (co ...

rendered by the GPU(s), causing the instantaneous

frame rate Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images ( frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also ...

of the longest delay to be significantly lower than the frame rate reported by benchmarking applications, such as

3DMark 3DMark is a computer benchmarking tool created and developed by UL, (formerly Futuremark), to determine the performance of a computer's 3D graphic rendering and CPU workload processing capabilities. Running 3DMark produces a 3DMark score, with h ...

, as they usually calculate the average frame rate over a longer time interval. In lower frame ratesUnder which frame rate the effects of micro stuttering become apparent varies depending on numerous variables and how sensitive the human test-subject is. The worst-case scenario would be that the frames from all GPUs finish rendering at the same time, in such a case the frame rate perceived by the viewer would be half of the reported average frame rate in the case of a dual-card configuration, and just a fourth in a quad-GPU configuration. when this effect may be apparent the moving video appears to stutter, resulting in a degraded

gameplay Gameplay is the specific way in which players interact with a game, and in particular with video games. Gameplay is the pattern defined through the game rules, connection between player and the game, challenges and overcoming them, plot and pla ...

experience in the case of a

video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...

, even though the frame rate seems high enoughThe generally accepted average frame rate for a smooth experience varies from game to game and user to user but is generally 30-60 frame/second and higher to provide a smooth experience. Single-GPU configurations do not suffer from this defect in most cases and can in some cases output a subjectively smoother video compared to a multi-GPU setup using the same

video card A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer mo ...

model. Micro stuttering is inherent to multi- GPU configurations using

alternate frame rendering Alternate Frame Rendering (AFR) is a technique of graphics rendering in personal computers which combines the work output of two or more graphics processing units (GPU) for a single monitor, in order to improve image quality, or to accelerate the ...

(AFR), such as

Nvidia SLi Scalable Link Interface (SLI) is a brand name for a deprecated multi- GPU technology developed by Nvidia for linking two or more video cards together to produce a single output. SLI is a parallel processing algorithm for computer graphics, meant ...

and AMD CrossFireX but can also exist in certain cases in single-GPU systems. The effects of micro stuttering vary depending on the application and driver optimizations. Beyond dual-GPU setups, CrossFireX/SLI setups do not seem to be as affected by micro-stuttering; the frame rate variability in a three-way CrossFireX/SLI setup approaches the smoothness achieved by a single GPU. As of May 2012, with the latest release of hardware and drivers from

Nvidia Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...

and AMD, AMD's

Radeon HD 7000 series The Radeon HD 7000 series, codenamed "Southern Islands", is a family of GPUs developed by AMD, and manufactured on TSMC's 28 nm process. The primary competitor of Southern Islands, Nvidia's GeForce 600 Series (also manufactured at TSMC), ...

is severely more affected by micro stuttering than Nvidia's GeForce 600 Series. In tests performed in ''

Battlefield 3 ''Battlefield 3'' is a 2011 first-person shooter video game developed by DICE and published by Electronic Arts for Microsoft Windows, PlayStation 3 and Xbox 360. It is a direct sequel to 2005's ''Battlefield 2''. In ''Battlefield 3''s campaign, ...

'', a configuration with two GeForce GTX 680 in SLi-mode showed a 7% variation in frame delays, compared to 5% for a single GTX 680. A configuration with two Radeon HD 7970 in CrossFireX-mode, on the other hand, showed an 85% variation in frame delays, compared to 7% for a single card, indicating large amounts of micro stuttering. These results are reflected in the perceptual experience when looking at the video in output. The software program RadeonPro can be used to significantly reduce or eliminate the effects of micro-stuttering when using AMD graphics cards in CrossFire.

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References

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External links

Micro-Stuttering And GPU Scaling In CrossFire And SLI
– Tom's Hardware
Inside the second: A new look at game benchmarking
– Tech Report
How To Fix CrossFire Micro-Stuttering
– ShareNoesis Graphics hardware

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