Check out this thread here with research about a 2700X:
Look for the section that is named "Where is the limit?". That section talks about the "FIT" machinery of the CPU. There's many sensors distributed over the whole CPU, and the FIT measures all of those constantly. It then makes sure to limit voltage when things get dangerous.
On that one particular 2700X that the article is about, that CPU's FIT was limiting things to below 1.330 V in the worst case. For that 2700X CPU, those 1.330 V would then be the limit you shouldn't go over when doing a manual 24/7 overclock.
Those 1.33 V are perhaps the kind of limit you should also choose for your manual overclock. I'm thinking maybe reduce it a bit more to be extra safe, because every CPU is different. Those 1.330 V were just for that one particular 2700X CPU, it's different on a different CPU. Perhaps choose 0.02V lower, so 1.310 V?
Ideally, you would test what the FIT of your CPU thinks about heavy all-core loads. But the 2700 has the problem that AMD has limited it artificially, and it will refuse to boost for all-core loads, I think? That's different on the 2700X.
My guess would be that 1.45 V is not a safe 24/7 voltage. It's much too high, it's only safe for low loads but is not safe for heavy loads. The voltage that's safe for everything, including heavy all-core loads, is perhaps more towards 1.3 V, so a lot lower than the 1.45 V you are thinking about.