If you have 3 normal computers, two of which are laptops (prone to overheating) take a look at some HDD coins that can be mined with your drives (no overheating and even a laptop can manage 24/7 mining).
interesting... can you give examples of these HDD coins, are they really profitable?
maybe no cpu/gpu overheating, but wouldn't the use of drive would generate heat on the drive itself
and the result would shorten lifetime of the drive itself too
so sacrificing drive costs less?