20 to 40 degrees of what? Fahrenheit or Celsius? If it is Celsius than the difference is way too much. Don't forget that new machines need some burning in time. Spotlight will be run an index on the disk(s) which will also cause high cpu usage -> heat -> fans going wild.
@MJL: poorly designed by your standards 😉 It is a subtle but very important difference. These machines are designed to last for x years with a constant heat of x Celsius (or Fahrenheit or Kelvin or whatever you want to use). Don't forget that during the assembly the electronics are baked on the circuitboards using very high temperatures, several times. This is only for short periods, the problem is heat over longer periods. I highly doubt that temperature differences of 2~5 degrees Celsius will make a big difference in the lifespan of the device, especially if we are talking 65 vs 70 degrees.
