If you are not overclocking, then the stock cooler should be fine, HOWEVER, given the probable age of the cooler, the fan may be getting weak. Since the cost of a decent fan is probably a big chunk of the cost of a whole new cooler, then a better cooler might not be a bad idea. 81°C on a system that isn't overclocked is too high, especially for an i5.
I would not recommend the 212 EVO though. That is to say, it's much better than the stock cooler, but it's probably not the best choice for the money, or, you can spend less, and get a BETTER cooler.
I'd recommend the Deepcool Gammaxx 400, if you don't want to spent more than 30 bucks.
PCPartPicker Part List
CPU Cooler: Deepcool - GAMMAXX 400 74.34 CFM CPU Cooler ($22.89 @ OutletPC)
Total: $22.89
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-07-10 03:17 EDT-0400
But if you don't mind spending a little more, this would be orders of magnitude better.
PCPartPicker Part List
CPU Cooler: Thermalright - Macho Rev.B 73.6 CFM CPU Cooler ($49.90 @ Amazon)
Total: $49.90
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-07-10 03:19 EDT-0400
No cooler can do it's job well though if you don't have good case cooling and airflow. Plus, a lot of cases won't support these taller coolers.
What is your case model?
How many case fans are installed and what is the orientation of airflow for each case fan, intake or exhaust, for each location?
What is the ambient temperature of the room your system is in?
A temperature of 81°C is a cause for concern, but I still don't think it is the root cause of your problems, as anything below 90°C, while possibly higher than we'd like to see, is not going to cause a specific issue like the one you are experiencing.
A faulty motherboard or graphics card is a lot more likely. Or even a problem with a borked up registry in windows or a bad driver.
I'd start with the clean install of the graphics card drivers and do it EXACTLY as outlined in my tutorial.