For our temperature testing, we measure the peak GPU core temperature under load. A reading under load comes from running the 3DMark Time Spy stress test for 30 minutes.
In terms of thermals, it's hardly a surprise to see the Toxic offering sub-70C operating temperatures regardless of the BIOS used. The Performance BIOS gives the lowest temperatures, as a result of its increased fan speed, while the Quiet BIOS is the hottest-running option as it significantly decreases fan speed. Toxic Boost is still hotter than the Performance BIOS as a result of its increased power limit and operating frequencies.