I'd say it does a terrible job. I'm using the stock cooler with my i5 6500 for aprox. a month now and it started to let the CPU run very hot a few days ago. This cooler seemed to work in the first weeks, stabilizing CPU temps at 60 degrees celsius on full load and 36 or so while idle, but now I get 45 idle and 80+ on full load with CPU throttle as a bonus when trying to play some games.
I tried to solve this changing thermal paste and fiddling with CPU configuration through software from ASUS, to no avail.
Stock coolers are just trash, unless someone can tell me how to get normal temperatures once again with one of these (which I'd very much appreciate).
My build is as follows:
CPU: Intel Core i5 6500
Motherboard: ASUS H170-Plus D3
Graphics: ASUS Strix GeForce GTX 960 2GB
RAM: Kingston HyperX Blu 1600MHz 2x4 GB
Data Storage: 2x1 TB HDDs
PSU: Corsair CX 500