Waitwaitwait... you have been sold a computer ... with graphics cards? A standard computer?
Scrypt mining on "normal" computers is dead. Did the guy told you? How much did you pay for it?

Odds are the fans are worn out. Maybe you could try changing them but in general hi-end cards are just noisy. If your card is say a 290x or a 290... there's little you can do. Those are noisy and will stay noisy.

Also try different algos, they tend to produce less heat.