I don't know what else you expect me to say.
If Steam declares a game is "unsupported" but it runs perfectly fine, I don't know what other way to describe that than "inaccurate".
Crowdsourcing is obviously far more effective if you simply look at the ratings on SteamDB.
Which GPU? How many drives?
Put a kill-o-watt meter on it and see what it says for consumption.