Yah I may not mine with these for three years however I'm not trying to destroy them either.
I understand your point, it has some merit.
Counter to that, I mine to make money not save a circuit board for the grandkids or for the manufacturer to send me a thank you note for taking care of my capacitors.
The unmistakable constant rise in bitcoin over the long term means that anything you make now will be worth much more later.
You may be earning $100 a week, after 3 years you look back and in fact you were earning at "today's" prices
$1200 a week.Keeping fans under x% / low power to "prolong life" is the height of folly as far as I'm concerned.
The more btc you earn now the better, and a
small increase in the hash rate will pay you massive dividends later on.
Replacing a fan with a $3ebay one is easy for anyone who mines. Should it die, put the old fan back on and send in for replacement.
If cards die get them cross shipped with replacements, hardly any downtime.
Sell when there is 6months warranty left, (evga's is transferable, making for increased resale value to gamers) and use the funds to buy the latest cards.
These are machines for working not pets that need looking after.