Hi,
http://www.videocardbenchmark.net/high_end_gpus.html I use the GTX970 on my fun machine. The music machine has the GTX960 which rates quite below the top cards.
The GTX 970, for example has driver issues ... if you check the purple onion stuff and other tests, it does fine, but on World of Warcraft, on zone "changes" it has a nasty hesitation, which would suggest bad code design, and poor integration with the vide cards.
That hesitation does show up in music. For example, if I load up one of the radio shows I have from 1974 and 1975, and they are highest quality mp3, somewhere in the middle of it, there is a hesitation every so slightly ... when playing them on Sonar. it does not happen when these are played on that other free program over the internet, that records and such. (not a daw!).
So, I can not tell you, right now ... which is the issue, but since Sonar/Cakewalk won't discuss video at all on their software, makes this whole thing a bit ... strange. I, personally, think that the main windows on every DAW, are too busy for the video card, but I doubt they are busier than a World of Warcraft raid with 25 people, for example, and the game has video settings that allow you to turn down the quality of the video, which a DAW, normally, would not require high quality, or the best. is my thought.