You should have quite different thermal expansion coefficients on the liquid metal paste and the silicon. Dropping temperatures stiffens the LM-TIM and the different thermal expansion does the rest and leads to failure in the connection (mikro delamination) - On the other hand it is the best way for the 24/7-overclocker to engage better temps, sure... So for Sub0 the long-established GELID should also do a good job on both sides of the IHS.