You are loosing some performance without the boost enabled. If it's overheating you must have something wrong with your cooling as that cooler is good enough even for constant OC up to 4.2GHz.
Check fan speeds at higher temps, fan should run full speed at anything at or above 60 - 65c.
Check if core voltage is not too high at full boost, some automatic settings can push it above 1.5v. which is unacceptable, shouldn't go above 1.4v.
Recheck cooler mounting and eventually change paste to something better like Noctua NT-H1.
X models of CPU have 2 temperature readings on with 10c offset and many programs don't compensate for it so your actual temps you should care about may be 10c lower.
HW Info
https://www.hwinfo.com/download.php can show you both, look for CPU (Tdie) which is one you have to worry about and CPU (Tctl) which is used internally for XFR to decide on boost level and keep things safe.