I don't know what it depends on, but I've written about a fairly high temp before.
There was a drastic improvement in version 5.3.002 the previous 5.2.xxx also had a temp around 69 to 71 deg.
Now (5.3.002)it is almost constant 65.
I don't know why 5.3.003 jumped all the way up to 74, 75.
Maybe...