One card running Hot

I have 4 8GB RX580s:
1 Powercolor Red Devil
2 XFX
1 Gigabyte

1 of them is running hot.

  1. How do I tell which one?
  2. How do I correct the issue?

It used to be GPU 2 and I took a look at the rig and a power cable had stopped one of the fans so I shut down the rig, rerouted the cable and fired it up. Now it is GPU3 that is running hot. Not sure if it actually the same one but just changed GPU# assignment or if there is an issue with a different card.

every time you boot you see a list of commands…one of them is fan detect or sth similar. it rotates fans so that you can detect which card in the rig is selected

For a RX580 try lowering the VDD to 830. (900 is for RX480`s)
And did you flash new timing strips to the Bios?