It's pointless when you have a single 4gb card which isn't powerful enough to use all of the 4gb. It's useful in crossfire, because every time you crossfire 2 cards this happens: 2gb+2gb 4GB, but you can use only half so you end up with only 2GB. With 4GB cards you get 4gb and 4gb 8gb and you end up using 4gb which can be handled by 2 cards together.
im not the only one who wants you to shoot yourself in the foot for that explanation, plus the gpu still cant use the 4gb. even if its in xfire
the Vram does not add together and only allow you to use half, its each gpu to there own, with the only exception to Vram being that if you have a 2gb card and a 4gb card, you will only have 2gb on both cards.
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