Okay, I'm a little tired of the "Fedora Neckbeard" stereotype, so let's set the record straight.
Not clear yet? Okay. This is someone in a fedora.
This is a douchebag. Notice he is wearing a trilby.
So to get this straight, neckbeard douchebags more often wear trilby hats. They are taller and their brims are not as wide as fedoras. Fedoras typically have a band around the hat, and they are more often pinched.
Now, I'm not saying that these are mutually exclusive. There can be cool guys in trilbies and douchenozzles in fedoras, to be sure. I'm just saying that most of the time, if you see a neckbeard, he's in a trilby and not a fedora.