Quote Originally Posted by Iconyu View Post
Nope they have memory controllers that each handle 64bit, Titan will have two more memory controllers than the 256bit part.
Usually there is a correlation between memory controllers and the amount of memory used on a card.
384bit=3GB/6GB with 12/24 chips

If you want to use 4GB with a 384bit interface, there will be performance problems if the last GB is addressed, because it is not full bandwidth. 2GB on a 384bit interface doesn't make sense either. Either you have 1.5GB full speed and 512MB at lower speed or you have 1/3 of your memory controller doing nothing, consuming energy.