For our temperature testing, we measure the peak GPU core temperature under load. A reading under load comes from running Cyberpunk 2077 for 30 minutes.
As for thermals, we have tested both BIOS modes on each card here, and to be honest there's not much difference between even the best and worst results. The Suprim X does run coolest out of the box when using the Gaming BIOS, with a GPU hotspot of 81C, but at worst using the Silent BIOS, the hotspot only hit 87C. Palit's results are right in the middle, with just a 1C difference between its Performance and Silent BIOS.