i really don't believe it's a temp thing, mid 60c is perfectly fine, im running 60-65c across all my cards.
now when you say the system dies? what happens? stutters? freezes? cant use it at all and a forced restart is needed?
The rig in the small room freezes. can't move the mouse sometimes. screen goes black and just have to power it down and force restart.
a couple cards run at 78 degrees, couple at 75 degrees and some near 72 degrees. depending on where i put big fan.
I've reinstalled drivers a few times.