I have 4 identical RX470s, running in the exact same machine, and under the same test settings. 3 of the cards all score around the same, but 1 scores around 500 points below the rest. Why would one be doing so much worse than the other 3?
The are used. They have the latest BIOS (all the same one) flashed onto them. I am not sure if they were used for mining, I am going to assume they were used for mining.