If i buy an Intel Core i5 processor from Amazon, will it come with a heatsink? If it doesn’t, is it really necessary to have one?
If you buy boxed version of Intel processors,you'll definitely get a heatsink.It's very necessary that you take utter care of your processors,else it'll fail before is warranty period which Intel might not recognize it.
Have a careful read on the below article which discusses this important serious issue.
Two Ways to Cool Down Your Defective Overheating Intel CPU
You can slow down the temperature by using aftermarket cooler with good heat paste(one that comes with aftermarket or Artic Silver 5).
They usually come with a heatsink. And yes, the heatsink is necessary for operation.
You should always take a good look at the product information as there are two version being sold.
This is the standard packaging for retail. These versions do come with a heatsink and thermal compound (which is actually pretty good and doesn't require third-party compound) and are intended for the end user. They also have a 3 year warranty for manufacturing defects (of course overheating or physical damage is not covered).
This is the package intended for OEM. They usually cost a little less since they don't come with a heatsink or a thermal compound. Most importantly however is that OEM versions do not come with manufacturer warranty. Extend and period of the warranty is up to the vendor selling them.
This really comes into play as tray versions are not always sold in the standard box. On occasion they are sold and shipped in a simple CPU clamshell which does not offer much protection.
You can identify the version being sold either by the name or by the ordering code. The retail code usually starts with 'BX' e.g. BX80646I54440 wherein the OEM code starts with 'CM' e.g. CM8064601464800
Yes, it will come with a heatsink & fan, and yes, it is absolutely necessary to use them! i5's produce approximately 90W of heat, and without a cooling system they will heat up beyond the spec. in a fraction of a second and shut down (all modern processors have a thermal cutout as part of the circuitry). The reason other coolers are available is because they offer some advantage: quieter, better air circulation or just nicer looking!
Beginners Guide: How To Install/Remove Intel Socket LGA1155 CPU and Heatsink
Intel Core i5 in box comes with intel heatsink, you always need fan to cool cpu, if you are heavy gamer...then perhaps you need to purchase another fan with better properties.