Just a wild guess, since I'm not very acknowledged on this ACPI
matters, but is it possible that the time it didn't work you had
previously booted without the parameters? It seems to me that the
kernel/something changes some ACPI configuration that is only restored
after a complete shutdown, and the parameter won't work if you simply
reboot.
BTW, by "not work" you mean it heats to the point of a shutdown or
"just" that it gets hotter than you expected?
Just a wild guess, since I'm not very acknowledged on this ACPI
matters, but is it possible that the time it didn't work you had
previously booted without the parameters? It seems to me that the
kernel/something changes some ACPI configuration that is only restored
after a complete shutdown, and the parameter won't work if you simply
reboot.
BTW, by "not work" you mean it heats to the point of a shutdown or
"just" that it gets hotter than you expected?