> That heat was minimized; cards were clocked (and voltages tweaked) to optimize the ratio of crypto output to Watts input. For Ethereum, this meant undervoltin

> That heat was minimized; cards were clocked (and voltages tweaked) to optimize the ratio of crypto output to Watts input. For Ethereum, this meant undervolting and underclocking the GPU -- which are kind to it. > Fan speeds were kept both moderate and tightly controlled; too fast, and it would cost more (the fans themselves cost money to run, and money to replace). Too slow, and potential output was left on the table. In the ideal case, this is spot on. Annoyingly however, this hinges on the assumption of an awful lot of competence from top to bottom. If I've learned anything in my considerable career, it's that reality is typically one of the first things tossed when situations and goals become complex. The few successful crypto miners maybe did some of the optimizations you mention. The odds aren't good enough for me to want to purchase a Craigslist or FB marketplace card for only a 30% discount. I do genuinely admire your idealism, though.