Thermal Stuff

[Kimikomon]

Since I will be using i5 9400F for my build and I don't really want to buy CPU Coolers so will the Stock cooler be enough? 

And how to check CPU temps

And what are the ideal temps for i5 9400F

[Firewrath9]

yeah the stock cooler should be fine, although there are a lot of good coolers for about 20-25$ that will be much much better than stock. anything under 60-70c is optimal. 80-90c is fine, 100c is big no no.

I use AIDA64 to check my cpu temps.

the UI for your GPU (I use radeon) also should have a OSD with temps and stuff.

[TheGlenlivet]

Cool yes.  Quiet, no.  If noise is no issue to you then the stock cooler is fine.  If you want something quieter then there are $30-$50 options out there that are better.