80C is fine for benching, real world temps will fall in the low to mid 70s.
The H7 is a fine mid-range cooler, but my guess would be your system is running a little high on the voltage. Mine booted up for the first time at 1.38 (which is what I seem to have settled on for 5.0Ghz, still tweaking though)
I've seen numbers as low as 1.2022 volts for 4.8Ghz, not sure I believe that. Anyway, run your bench and see what the core voltage is getting up to. Since you are pretty much already at the thermal safe zone, you can use that as a maximum. Then you should run the voltage down until the system becomes unstable. Or go ahead and shoot for your target overclock and see if it just works, then back the voltage down from there.