20 is about the best you will do with a 1060.  Probably run it around 75% power.  The thing that is going to fail on your card is almost certainly going to be the fan(s).  Try to keep them around 50% speed but still keeping your GPU around 70c.  If you think about the effect of mechanical wear, it probably works like any other form of kinetic energy - based upon the square of the energy.  Ie., my guess is that a fan running at 50% will last four times longer than one running at 100%.

Not really totally sure on that, but what little I remember from physics seems to somewhat jive with that idea.