What heatsink should I get for my new computer?

Unless you are going to overclock your system to a very high speed, any decent aftermarket CPU cooler will work just fine. I highly recommend Noctua, but there are many, many, quailty coolers out there. Find a couple you like, and the do a bit of research to find the best one. Just make sure they are compatable with your CPU. BTW please ignore that pile of junk the last poster suggested. I have a feeling that person has never built a computer. No one in their right mind would ever put that on a high end gaming computer.