Where's the smartness when you lose half the frame buffer for 30$?
Have you seen how games utilize video ram nowadays? I am not saying that they actively need more than 4GB to render high textures with high settings, but they can easily use excess video ram to store important data that will be requested later.
In any case, if someone is buying Hawaii, I don't see the point of not opting for the 8GB model, to give himself some future proofing.
Some people may think that such a card will run out of gpu power long before it runs out of vram. This may turn out to be true. I believe we have all seen that the most important setting that makes a game ugly, is the texture quality setting. Something that affects video ram usage directly. Why would someone want to risk that for 30$?
jack enough assets to fill that 8gb vram, and that single 390x gpu will be choking. reduce enough asset to have that 390x singing and vram will be half empty.
the point is you have absolutely no practical use for that extra vram.
bottom line is. it is your money. spend it as you see fit. even if it has zero performance improvement, perhaps the bragging rights are worthwhile.
obviously we are all guilty of spending way way to much on bragging rights. at least some of us did not buy into it blindly. we actually knew we were buying bragging rights.