NVIDIA have released driver version 331.65 which enables a beta version of "ShadowPlay" which is only available on the 600/700 series of NVIDIA graphics cards. ShadowPlay allows the user to record any game with very very low frame rate drops and doesn't put much load on the computers processor or hard drive, as it uses a small bit rate. ShadowPlay takes advantage of a H.264 hardware encoder on the actual graphics card and allows recordings in 1920x1080 (1080p). At the moment it's in beta stage so there isn't much customization available, there is only a set resolution and you can't add a microphone to record, you can only have game audio. There is another feature of ShadowPlay which makes it stand out, which is the shadow recording mode. This mode means that if you have ShadowPlay on, running in the background and shadow recording is on, that means that if you get something really cool in the game you are playing and you weren't recording, if you press the shadow recording key it will save a recording of however long you chose beforehand. For example you can have the shadow recording to last for 10 minutes like this,
this means that ShadowPlay will constantly be recording for up to 10 minutes and anything after that will get deleted and if you chose not save the shadow recording then there won't be any file. You can have the shadow time any length up to 20 minutes, but the longer you have it on for the bigger the file size will be. You can also set the quality of the recording which will make file sizes bigger or smaller depending on what quality you choose.
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I use it as well.