4 ms·
Speed and size are somewhat independent. Speed is set by the bus frequency and how many chips you use - every chip has a fixed data bus width, typically 32 bits
by throwawayish 10y ago
Speed and size are somewhat independent. Speed is set by the bus frequency and how many chips you use - every chip has a fixed data bus width, typically 32 bits, while overall size is then how many chips you have times how big each chip is.
Unlike typical computer memory architectures, where the memory bus connects multiple chips or modules to one controller, GDDR doesn't do that; every slice of the memory controller only speaks with a single chip, strictly point-to-point. (Reducing bus load and layout issues and thus allowing higher clock rates).
That's why, with GPUs, it's usually sufficient to say how wide the bus is (often 64 - 128 - 256 - 384 - 512 bits) to get a rough idea of it's performance, since memory clock frequencies occupy a rather narrow range. (However, narrow-bus, lower-end GPUs often don't use the same technology as higher-end GPUs, eg. DDR3 instead of GDDR5)