Theoretical Bandwidth Calculation

Theoretical bandwidth can be calculated using hardware specifications available in the product literature. For example, the NVIDIA GeForce GTX 280 uses DDR (double data rate) RAM with a memory clock rate of 1,107 MHz and a 512-bit wide memory interface.

Using these data items, the peak theoretical memory bandwidth of the NVIDIA GeForce GTX 280 is 141.6 GB/sec:

(1107 x 106 x (512/8) x 2) / 109 = 141.6 GB/sec

In this calculation, the memory clock rate is converted in to Hz, multiplied by the interface width (divided by 8, to convert bits to bytes) and multiplied by 2 due to the double data rate. Finally, this product is divided by 109 to convert the result to GB/sec (GBps).

Note that some calculations use 1,0243 instead of 109 for the final calculation. In such a case, the bandwidth would be 131.9 GBps. It is important to use the same divisor when calculating theoretical and effective bandwidth so that the comparison is valid.