There's no goal post shifting involved. 1080P is the most popular monitor resolution by far. And right now, 4GB is the highest amount of VRAM on cards that have been sold in great numbers. Game devs aren't going to release a game that doesn't look good or perform well at 1080P with 4GB of VRAM. 980 SLI doesn't seem to need more than 4GB of VRAM. So a single 390X with 4GB hardly seems to be any sort of limitation. Only those who play at 1440P or above will really need more than 4GB of VRAM for the foreseeable future, IMO.I'm SO glad you mentioned this...
The argument you're making now is the same one that could have been made for the 680/7970. When it (680) was released it was faster and cheaper than the 7970, but with less RAM. But it didn't maintain that performance lead, especially now with games using more than 2GB of VRAM even at 1080p
That's basically what you're saying about the 390x... It might be faster and cheaper but with less RAM than the 980Ti
Yet for some strange reason, the AMD fans are all in agreement that anyone who bought a 2GB 680 at the time probably made the wrong choice, however, that EXACT same scenario playing out now, only in reverse, and they don't see a problem.
Oh how the goal posts shift...
If what you theorize is true, everybody who bought a 970 with its 3.5GB + 0.5GB memory are going to be in even worse shape than the 290/290X owners with their full speed 4GB of memory.
