Installing Heatsink/Fan atm and need an answer

You don't use a thermal pad if you're using thermal grease.
Apply a thin amount coating on the heatsink on the parts where the heatsink will make contact with the CPU.

Make sure the thermal grease is a good type.

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"Now drop your weapons or I'll kill him with this deadly jelly baby."
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actually you can put a little on your finger and rub it into the bottom of the heatink where the cpu die is making contact, thus filling in any tiny cracks or blemishes on the heatsink that you cant see with your eyeballs. I believe this method is recommended by the people who make Artic Silver. Go to their website and read the application procedures, should be the same for any grease.