Tech question de lids

How hard is it to install a CPU cooler on a AM3 board?
Do i need to take the motherboard out to install rear mounts/backing plate?

I bought my PC a few years ago 2nd hand at a good price
>AMD 3500x
>16GB RAM
>GTX1080
>SSD

Lovely little shitter but the CPU cooler looks fucking tiny (Pic rel)

If i play anything cpu intensive for more than 30-60 minutes there's a good change the PC will restart

Tried to run temperature software to see whats going on and the CPU likes to hover around the 80c+ mark when gaming, i think the thermal limit is 90c so when things get busy it must spike and shut the cunting thing off

No idea why its a 3500 and not a 3600cpu, ever other AMD CPU of this age/specs have the slightly bigger coolers with the fancy RGB fan included