"Rust" specifically is "Ferric oxide". And while I expect copper to be susceptible some form of oxidation, there isn't that much iron or steel present on PC components. The mobo to case screws and the CPU clip are steel , and that's about it. Tin, lead, and aluminum might react long term, but not in the span of a dishwasher cycle. The mounted electronic components are covered in waterproof dielectric materials.What about oxidation and rust?
I tried this with my mobo long ago in the shower but it actually died. Maybe I didn't take out the battery? Or put the cpu protection as they suggest, or maybe I didn't let dry enough?(gave it 24 hrs). Who knows, but I've never tried such a thing again. Period.