They also sometimes do GPU BIOS modifications, which is a fun thing to discover once the card ends up on the second-hand market and you happen to buy one. Luckily the fix is to reflash the BIOS using a matching one from TechPowerUp GPU database, but this assumes that you even know that this is something to pay attention to.

Source: happened with an RX 560 that I bought second-hand. Driver installation failed in Windows 10 due to the modified GPU BIOS. Was fixed with a reflash of a stock GPU BIOS using atiflash.

Any idea what they modified?

I didn't check it, but if I had to guess, it might have to do something with allowing the card to run using settings that make it more suitable for mining. Someone more familiar with GPU mining can correct me here.

Usually memory timings, at least on my 5700 XT

Totally true- I went through the process of manually overclocking my 2080ti for max hash rate and the best settings involved setting a power limit that is less than half the card’s 100% limit.

> Heat is their enemy

Sometimes literally: https://www.youtube.com/watch?v=fr8bp8a2QS4

"A Bitcoin Miner Heatstroked In His Sleep. This Is What Happened To His Organs."