setting high temperature threshold before server self reboot

[sunhux G]

> to find out why it's getting so hot and remedy that.
It's been years that servers in this rack doesn't have any heat or
blown parts issue till a few days ago, 2 other servers in this rack
blew their Power Supply Unit.  I'm suspecting the smoke from the
blown PSU could have been siphoned into a couple other servers
which triggered another PSU failure early this morning & this
Linux box to self-reboot (perhaps it siphoned it some smoke)

>Are one or more fans out? Has the room a/c failed, or is intermittent?
Nope, it's generally 19 Celcius & all other servers in other racks are Ok.