Do I have to buy a CPU cooler separately?

Question

I bought the Intel i7 7700K Processor off eBay with the following picture:

And a GA-B250-D3H motherboard.

Is a brand CPU cooler/heat sink included in any of these packages or you always have to buy it separately?

How about thermal paste?

Answer 1

Skylake (6xxx) and newer K-series Intel processors do not come with heat sinks. K-series processors are targeted at overclockers (that's the only thing the K designation really means) and Intel knows that including a cheapo heat sink in the box will result in an unfortunate amount of aluminum being discarded.

Nearly all of Iuppiter Zeus's answer is on the money except for the fact that your processor will include a heat sink and fan. It will not unless specified by the seller. The Hyper-212 outclasses all others in its price range. If you are looking to get heavily into overclocking and invest in something $100+ there are dedicated forums I'd suggest you look into; for anything short of that the 212 will serve you well.

I would also clarify that nearly all heat sinks will include thermal interfacing material (TIM; or "thermal paste"). What comes in the box is perfectly fine unless you plan to tinker with your overclock for max performance. 3 grams is a lot of paste, by the way. Use about a grain of rice.

Answer 2

To me this looks like a "boxed CPU" which means that there is a cooler included. This so called "stock cooler" works fine but is very low quality and loud. I personally don't recommend using it.

Especially if you overclock your CPU (which I suppose because you bought the K version) I would invest into a tower cooler. They offer a way better cooling performance (→ lower temps, higher stability, more overclocking headroom etc) and are usually a lot quieter.

Personally (on a AMD FX-8350 which is "famous" for getting hot) I use a bequiet Shadow Rock 2 but something like a coolermaster Hyper 212 Evo might have been the better choice. But make sure it fits into your case (usually the case manufacturer mentions info like a "max. cooler height").

About thermal paste:
There might be some already on the heatsink. I'm not sure if intel does that. But I don't recommend using that either (probably you can't even use it because it's on the stock heatsink). There are good ones available on the internet, just search a little while (I guess you know linustechtips, he recommended some).

Just one little tip for that: Don't buy more because it's cheaper per gram. You need so little amounts of it, like 3 grams is enough.