Noctua Nh-d14 plastic spacer, remove or keep?

[zoog18]

Hello, I am about to install my Noctua NH-d14 and I noticed that their are plastic/glue like spacers in the heat fin towers, do I remove these? Or keep them on?

 

[clonazepam]

Those are what the fans make contact with, instead of the fins themselves to reduce noise.