Memory Bandwidth: Memory bandwidth is the max amount of data (in units of MB per second) that can be transported across the external memory interface in a second. It is worked out by multiplying the interface width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Taking a base frequency of 400Mhz
800MHz (effective) DDR3 * 256 = 204800
1600Mhz (effective) DDR5 * 128 = 204800
Practically the same, until you notice new DDR5 cards have higher base freq than old DDR3 cards, regardless of bus width
GDDR5 FTWEdited by ronnin426850 - 8/23/11 at 10:19am