Why does Freesync match the framerate rather than double it when possible?

[chivs688]

Researching into Freesync as looking into getting a new monitor, and came across the TftCentral review of the Asus MG279Q. In this the reviewer points out the greatly increased lag as the refresh rate is lowered.

This got me thinking, if this is commonly the case, then why when possible does Freesync not run the monitor at double the current framerate?

So say if your game is at 64fps, why not set the monitor at 128hz? Same smooth experience, but less lag and more 'connected' feel due to the higher refresh rate?

I know there is this frame doubling when below the threshold, but not 100% on that and why it would be used only below the threshold and not always below half the monitors maximum refresh rate, if it is in fact the same as what I'm talking about above.

 

[chivs688]

Probably because the input lag is coming from the video card, not the monitor.
And its coming from the FPS cap.
And image quality wise, same reason why double strobing sucks so much.
You get a double image. I don't know why there would be input lag, though.

But in the review it states that its 'Signal Processing Lag' that increases, which sounds to me like a monitor process rather than to do with the graphics card. Although can't find out exactly what they mean from the googling I've done since reading it.