None, but that'a not what computers are. C assumes that in a few places, e.g. variadic functions, and those are the worst parts of the language.
Which language more accurately represents hardware then?
The real answer is obviously Assembly - pick a random instruction from any random modern CPU and I'd wager there's a 95% chance it's something you can't express in C at all. If the goal is to model hardware (it's not), it's doing a terrible job.