Various machines reboot randomly all the time. Given the amount of direct outdoor airflow that we push through the machines (we don't have fans on the GPUs), as soon as the GPUs stop running, they cool down very very quickly. That is the 'shock' you're looking for.
Why do they reboot? We run on the edge of peak OC tuning performance by default and I've built an automated tuner which downclocks individual cards. This way, they get more stable over time, while maintaining their best possible performance.
Occasionally, we would reset the tunings and then let them auto tune back... this accounted for the seasonal variances because hotter cards are more prone to crashing.