History of cold boot attacks on Proof-of-Stake miners Have instances of theft due to cold boot attacks been recorded?  If so, is this a common problem?

If so, are miners installing memory encryption software like Trezor?
It's not an appreciable issue. If somebody has physical access to a a miners server rack, it's game over no matter what "memory encryption" is used. As for the attack specifically, I doubt it's ever been used outside of security demonstrations and high level infiltration rather than something as completely insignificant as Bitcoin mining.