It's not true that computer randomness is predictable, all recent computers have entropy sources which are essentially quantum in nature - thermal noise.
Edit: I think figure 3 in this study is what I'm looking for. They define the inconsistency I described as "spectral pivoting".
> This discrepancy is because the Mermin-Wagner-Hohenberg theorem holds in the thermodynamic limit, while these simulations are for finite lattices
I think thermodynamic limit here means, it needs to be way too hot?