What started as an arcane debate among hardcore hardware spec analyzers has now become a legal headache for Nvidia. The graphics card maker is facing a class-action lawsuit in the Northern District of California over allegations that it falsely advertised the total hardware power in the GTX 970 graphics card released late last year.

In marketing materials and reviewer guides provided when the GTX 970 launched in September, Nvidia advertised a card that had 4GB of high-speed GDDR5 RAM. Earlier this year, though, many users online reported performance issues when trying to utilize the entirety of that RAM, including stuttering and crashing on games and video editing applications.

Subsequent analysis found that the GTX 970 actually splits its RAM into two segments—a high-priority 3.5GB segment that is indeed high-speed GDDR5 RAM and a lower priority 0.5GB segment with a data bandwidth that's roughly 80 percent slower. Some other advertised specs for the card also don't match the shipping reality: the GTX 970 has only 56 Render Output Units, down from an advertised 64, and a 1.75MB L2 RAM cache rather than the advertised 2MB.

Analysis by a number of websites suggest it's rather difficult for an average user to notice these issues when playing today's games. Unless you're running games at 4K resolution with low frame rates and high anti-aliasing settings, it's unlikely that any game you're playing now will be forced to use that slow, low-priority RAM (that might be less true for multi-card SLI setups, though, according to a PC Perspective analysis).

In any case, as game requirements continue to increase in the coming years, that last bit of slow RAM will likely make the GTX 970 a bit less future-proof than a card with the advertised full 4GB of high-speed RAM. Anadtech has an incredibly deep dive on what the spec discrepancies actually mean for the card's high-end performance.

In response to these revelations, Nvidia acknowledged the 970's unorthodox memory partitioning and lower-than-advertised specs but argued they had minimal impact on actual game performance. Compared to the GTX 980, which has a full 4GB of unified GDDR5 memory, Nvidia says the GTX 970 only sees an additional one to three percent performance dip when forced to use the slower, low-priority memory at the top end of its range. In other words, Nvidia argues, the slow memory doesn't result in much real-world impact at this point.

Separate from the actual impact on performance, though, is the fact that Nvidia shared some specs that were simply incorrect with reviewers and the public via its website. Nvidia chalks this up to an error in communication between engineers and the technical marketing team that provides those public specs rather than any intentional duplicity. Nvidia says the error wasn't caught in an initial check of that publicly released information, and it wasn't rechecked until the company received numerous user complaints roughly four months after the card was released.

That's not satisfactory for the plaintiffs in the class-action lawsuit, though, who say Nvidia "engaged in a scheme to mislead consumers nationwide." As the suit bluntly puts it, Nvidia "uniformly marketed, advertised, sold, and disseminated information that represents the GTX 970 to have specific capabilities when it does not," misrepresenting "a key selling point of the device" that would be important to a reasonable consumer's purchasing decision.

Even before the lawsuit, there were plenty of Nvidia customers angry about their less-powerful-than-advertised cards. A thread on the official Nvidia forums about the issue has ballooned to over 366 pages as of this writing— "how the heck am I ever suppose [sic] to know what the heck I am getting if they can lie in the spec's [sic]", writes one representative user. A Change.org petition asking for help from the FTC and the European Commission has garnered over 9,000 signatures so far.

"Nvidia purposely omitted essential information from their consumers, information which would not have been revealed if not for users noting unexpected behaviour of the hardware," the petition reads in part. "Now, in the days following the revelation, Nvidia still keeps insisting that this was not misleading omission and continue to refuse consumers their lawful right for a refund."

While the lawsuit seeks "corrective advertising or full refund campaign" as well as other damages, some retailers are reportedly offering refunds to disgruntled customers already. Meanwhile, competitor AMD has already taken advantage of the controversy, offering discounts on its Radeon cards for users who return a GTX 970. The rival graphics card maker has also been busy teasing Nvidia with promotional images noting that, at AMD, "4GB means 4GB."