When it is a dual GPU card is does. The memory bus of each GPU (384-bit) is multiplied by 2 because there is 2 GPU's. So, 384+384 = 768. I'm almost sure that the minimum memory for that bus size is 6GB. For another reference, the GTX 690 is dual GTX 680's. The 690 has 4GB of VRAM. Why? Because the GPU's share memory.