Testing memory bandwidth on video cards is tricky, but we’ve been dabbling around testing it in recent weeks. We built a new system to test just memory bandwidth it is best the test on a system that has a CPU with integrated graphics in order for the discrete graphics card can be run in headless mode. We also disabled Windows Aero and set the system to high performance mode for both the display settings and power settings. Nai’s GPU memory bandwidth test only works on NVIDIA CUDA cards, so we tested a handful of NVIDIA GeForce GTX reference cards from the Fermi, Kepler and Maxwell series to see how they perform.
We weren’t expecting to reach the theoretical peak bandwidth figures, but all of the cards came in reasonably close. The NVIDIA GeForce GTX 980 Ti is rated as have 336 GB/s of memory bandwidth and we averaged 289.2 GB/s across the 6GB frame buffer. This is a nice step up from the 178.8 GB/s measures on the GeForce GTX 980 reference card! No performance drop off was noted in the benchmark and we ran the VRAM bandwidth testing utility at block sizes of 16, 32, 64, 128, 256, 512 and 1024 just to be sure on each card.