gddrBandW = 32; //gddr5 bus width hbmBandW = 1024; //hbm bus width Test isn't really accurate. He's only factoring in bus width and not speed. While GDDR5 has a much smaller bus it's running at a way higher speed. A more accurate test would be 512/1024 for those parameters. As actual bandwidth comparison would be like 320 vs 640 or something. (290x vs FijiXT) This isn't to mention that games don't remove all texture elements from memory after being rendered.