Replacing stock cpu cooling

[dcsmith3]

As per the title, I'm putting in a new Corsair H50 for my cpu, but as I removed the stock cooler I noticed some residue on the cpu from the thermal sticker on the stock fan. Do I need to and how do I clean it?

 

[Engima]

Assuming that the "thermal sticker" is thermal paste then use some isopropyl alcohol and something lint-free, like a coffee filter, to wipe it off. It's good practice to remove the old thermal paste and apply new thermal paste if there is not a layer on the new cooler.