I would conclude that the Vizio has a better tuner than does the PC's card. The Vizio is able to handle signals that are either weaker or of poorer quality than what the card wants to see. Sorry, haven't worked with any PCI tuner cards.
You might try to see if changing the antenna's location makes a noticeable difference. Raise or lower it and see if reception improves. Try to optimize the antenna's location so that it has the clearest possible "view" back towards the signal's origin.
|