i5-750 should be okay at 80degC... Intel recommends roughly 75degC for CPU's of that generation (AFAIK) but if the CPU is working fine and presumably has been for what NINE YEARS or something why worry now?
*Why a choice between those coolers anyway? Why not something that would be QUIETER?
(It's not just cooling potential but fan noise)
https://pcpartpicker.com/product/hmtCmG/cooler-master-cpu-cooler-rr212e20pkr2
or
https://pcpartpicker.com/product/93Crxr/cryorig-cpu-cooler-h7
Make sure whatever cooler you get fits.
Instructions on install/setup:
1) remove old cooler
2) clean off paste with 90% Isopropyl Alcohol (70% is doable but takes longer)
3) if thermal PASTE add a "pea" sized (5mm diameter approx) amount in middle of the CPU
4) if thermal PAD make sure to remove the plastic protector, then
5) place cooler on top.. follow instructions to install
6) setup fan control (preferably using motherboard fan software from motherboard support site)
*for fan software optimize for relatively constant fan RPM in idle/light usage, then adjust so under heavy load it doesn't go past 75degC (for REALISTIC load not stress test like Prime95... if you use HANDBRAKE to convert video adjust at 100% CPU utilization for 5+ minutes)