Well, as far as "fall off easily" goes, it depends! The sticky stuff tends to get more plastic at higher temps, so it depends on how hot the RAM gets. Problem is that video memory runs a bit hotter these days.
You can for sure solve the problem by taking some nail polish remover and removing the sticky stuff. Then make a mix of 75% regualr artic silver and 25% artic silver two part epoxy. DO NOT exceed the 25% two part epoxy or risk marrying the parts forever.
And yes, it will help you clock higher without video memory artifact and the solution I give is a tad more efficient at transferring heat than the sticky stuff.