vargy :
that was my main concern with this method, but is there a way to make sure heatsinks don't drop?
It seems to me that the only way is to ask about previous experience from others.
I can also glue some non-conductive wires to the heatsinks and to the board this securing hem for good, but this method seems even more crude and completely irreversible.
If you properly use a
Thermal Adhesive which is actually 2 part thermal epoxy to secure the Ram Sinks it is a permanent solution, they will not fall off and will not come off without taking the memory chips with it.
The link above is non electrically conductive Artic Silver Alumina, a permanent solution, and to get the best Thermal Bond I recommend seating the Ram Sinks and then adding some type of pressure on them overnight, for maximum contact bond.
Make sure you understand this is a permanent solution you will not be removing these to return to your stock cooler.
Be absolutely positive that the Ram Sinks are as tall as possible to fit under your GPU cooling solution and still have clearance between their tops and the cooling fins
You want as much cooling as you can possibly get from the Ram Sinks, so even though you already have some, make sure they are tall enough, this is a one shot deal for you.
It's very important to thoroughly clean both contacting surfaces before applying the Thermal Adhesive, Q-tips and 70% isopropyl alcohol will do just fine, clean until you show no residual residue.