@ Bluestang RE Artic 5 paste.

Check out the website for good instructions on how to apply

I clean both cpu and heatsink with Isopropyl 1st
Then apply some to the heat sink, spread it and wipe it off with a lint free cloth
Then apply a very small amount to heat sink and spread it using the edge of a clean credit card or similar so even amount over top of cpu
Then fit heat sink!

If its a new cpu/heatsink combo I always remove the heatsink after fitting to check contact over entire cpu surface. If not then its time to lap something!!
If good, refit. You wont need to apply anymore paste, but I always clean and start from scratch.