Everything on a CPU is subject to heavy validation .. but I bet the random number generator is exempt, because by definition it's not deterministic. It's more like a peripheral "listening" to randomness.

https://www.amd.com/system/files/TechDocs/amd-random-number-...

> "The RNG uses 16 separate ring oscillator chains as a noise source. Each chain consists of a different prime number of inverters in a free-running configuration which capture natural clock jitter"

So it's (deliberately) dependent on natural manufacturing variation in the silicon, and in any deterministic simulator won't produce random numbers. It also takes a while to start; it's possible that the startup conditions are bad such that "a while" turns out to be "forever".