Filed with the U.S. District Court for Northern California, the suit names both Nvidia and Gigabyte as defendants. In PC World's words, the suit alleges that Nvidia "misled customers about the capabilities of the GTX 970." Although the card is advertised as having 4GB of RAM, the last 0.5GB "runs 80 percent slower than it's supposed to," which "can cause images to stutter on a high resolution screen."
The allegation about the memory bandwidth drop is correct, as far as I can tell, but Nvidia's numbers suggest the slower half-gig degrades performance only by about 1-3%. Nonetheless, the initial lack of transparency about the GTX 970's memory configuration has angered users, since the card was deliberately designed to run only 3.5GB of its memory at full speed.
PC World says the plaintiff in the suit "seeks a jury trial and whatever damages apply." If the judge gives the suit class-action status, and the plaintiff wins, other GTX 970 owners could be eligible for compensation.