Yup exactly. The only way independent hardware can help is if the fault is state dependent in a way on the hardware (eg differences in behavior due to thermal load or different internal state corruption or something) in which case repeated computations may not help if the repeated computation is not sufficiently decoupled temporally to get rid of that state. The other thing with independent hardware is that you don’t pay a 3x performance penalty (instead 3x cost penalty). That being said, none of these fault modes are what are really what is being discussed in the paper.

The other one that freaks me out is miscompilation by the compiler and JITs in the data path of an application. Like we’re using these machines to process hundreds of millions of transactions and trillions of dollars - how much are these silent mistakes costing us?

If it's consistent and persistent, wouldn't that classify as broken hardware requiring device change?

Even with 3 chips, if one is permanently wrong you are then left with only 2 working ones so no redundancy is left for further degradation.

> just compute 3x

That might be difficult if CPU is broken. How are you sure you actually computed 3 times if you can't trust the logic.