Ah, OK.
I'm just checking for correct functionality, infant mortality and probes are OK and compensated and correct colored rings attached plus adding my company sticker before dispatch. I do notice some fans are quieter than others.
Next one I unbox I will see if the fan model is visible and post it up somewhere so that those that wish they could be quieter can have a better fan replacement option.
As for HW variations, they could be anything.....think about it, new fan model, different PSU, LCD, keypad etc, etc.
Mods are always being made to improve products.