Apple silently rolled out a repair program for Mac Pro computers manufactured between February 8, 2015 and April 11, 2015. There's no dedicated webpage but several websites like 9to5Mac are reporting the news as Apple recently sent out repair details to its authorized service providers.
Affected Mac Pro systems suffering from video card related issues are eligible for repair, which consists of swapping out the graphics card.
In the notice, Apple notes that Mac Pros manufactured between February 8, 2015 and April 11, 2015 are eligible for repairs due to issues with the machine’s graphics cards that “may cause distorted video, no video, system instability, freezing, restarts, shut downs, or may prevent system start up.”
Apple goes into a bit more detail about the symptoms eligible for repair:
Distorted or scrambled video on the external display
No video on the external display even though the computer is on