I suggest you to watch some videos about thermal pads replacement on GPUs, like this, total related to mining:
https://www.youtube.com/watch?v=rH3Oavi-0OEUsually, manufacturers, didn't put the best thermal pad on their projects, and you can make significants improvements changing the thermal pad, and the thermal paste too
You'll reduce temps on memory for sure, but you have to use good pads, like Gelid for example
It's important to know the thickness to use in each card, if you put wrong one, you can make things worse, and another thing to consider, you'll probably lose the warranty of your card