I was thinking about this just yesterday
My 450G was operating @ 66-67°C for 3 days, when it suddently "rebooted" all by itself (and complained about a unclean shutdown sequence... O'Rly?!)
I don't know if it's related, as I upgraded from v4.17 to v5.4 a couple of days before.
The 450G documentation writes: Temperature range -20C to +45C
But it's not that meaningfull as my board is in a case and not opened to the sky...
I'm not willing to drill the case either, even knowing that room temperature can be much higher than it is actually :/