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.
Likewise, for the temperatures we have no point of comparison for the RX 7800 XT, but the reference card did well enough – the GPU temperature peaked at 76C, with the hot spot at 94C. That hot spot result is fairly warm but well within safe limits – I'm sure AMD's partners will be able to improve on this though.