You can try painting heatsinks but taking them off from motherboard might invalidate the warranty and also require replacing thermal tapes used to connect them with components they were cooling.
When picking a paint you need to make sure its right type for material that heatsinks are made of (especially if they are made out of aluminum) to ensure there wont be any reaction going on.
You need to either scrap all the old pain from them or again, make sure that new paint wont go into reaction with old one.
If your heatsinks are not painted but anodised you need to either scrap it or put a paint layer on it to prepare them.
Then your new paint needs to be heat resistant, you dont want it to start emitting chemicals when radiators heat up to 50 degrees or more.
But most imporant, adding new layer of paint might worsen your heatsink capability to dissipate heat. If you really want to customise them, and they are made out of aluminium, your best course of action (but not cheapest) is to have them re-anodised to what ever color you want.
Refer to these threads for more information:
http://www.overclock.net/t/1444839/painting-motherboard-heatsinks
Michael_671 :
....also a guy at frys told me a 7thgen cpu is better than a 6th gen but he gave me a non k. Can i take it back
I think you should be asking "a guy at frys" for that or whatever place you bought your cpu.