View source for Multiple GPUs

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== Multiple GPUs in [[iPi Mocap Studio]] ==
You can use multiple GPUs to speed up tracking with the following limitations:
* You can use only '''1''', '''2''' or '''4''' GPUs inside one PC. Other configurations (for example, 3 GPUs) are not supported.
* Dual-GPU video cards like '''NVIDIA GTX 690''' work in [[iPi Mocap Studio]] in the same way as 2 separate GPUs. The same instructions are applicable to such cards.
* For best efficiency, all GPUs must be of approximately the same performance. [[iPi Mocap Studio]] cannot balance load for multiple GPUs with different performance levels, so mixing low-end and high-end GPUs will result in very poor performance.
* Due to synchronization overhead, performance scaling is not linear. Performance gain diminishes with the number of GPUs.  Using second identical GPU will speed up tracking approximately by a factor of '''1.6''' (instead of factor of 2, as one might expect).
* Performance gain is more noticeable for large number of cameras ('''6+'''). If you are using just '''1''' Kinect camera (or other single depth sensor), you may even experience performance downgrade compared to a single GPU. 
* Combining multiple low-end GPUs makes little sense. You may achieve much better performance by upgrading to a single high-end gaming GPU like '''NVidia GTX 970''' and above.

== How to Configure Multiple GPUs ==

To configure your multiple video cards for use in [[iPi Mocap Studio]], you should perform the following steps:
# Disable '''SLI''' or '''Crossfire'''
# Restart [[iPi Mocap Studio]]. Now it should be able to use your additional GPUs.
{|
|[[Image:Disable_SLI.png|thumb|400px|How to disable SLI (click to enlarge)]]
|[[Image:Disable-Crossfire.jpg|thumb|307px|How to disable Crossfire (click to enlarge)]]
|}