Tuniq TX-2 Thermalpaste
 

The first time I turned my computer on with the TX-2 paste, I
noticed that the temperatures were better than they had been with
fully ‘burnt in’ Arctic Silver 5. So it would appear that the TX-2
needs little or no burn in time to reach peak performance. That is no
small feat!

http://www.xtremecomputing.co.uk/review.php?id=383