The usual making sure the fans are working (in the case, and on the card), and clearing out dust bunnies and the like, may help. Some cases have horrible ventilation so once they get warm internally it is difficult for them to expel enough heat (and suck in more relatively cold air from the room) to keep everything cool. Heatsinks get less efficient as the ambient (internal case air temperature) gets hotter, as the already warm air can not accept the heat energy as it is already "full" (heat soaked). If you've got a bunch of wads of cables everywhere inside, try dressing them a bit more out of the way of air flow (figure out where your case brings air in, and where it blows it out) you may also see a decent reduction in overall temperatures as the heatsinks are able to transfer heat more efficiently. Or, add more case fans to force more air in and out (many cases do not come with much, if any, in the way of extra fans and rely on the one built in to the power supply).
However if you do not have lockups or issues during hard GPU use (gaming) then I don't think you have a problem. Cooler chips live longer, but the way things are speeding ahead the card would likely be "old and slow" before it burns out anyway.