memtest is a pretty basic test and is not very reliable at triggering errors in memory pushed just past of what it is capable of. It's fine to run it as a smoke test before booting into the operating system (to make sure it won't crash right away), but after that you're gonna need something like TestMem5. I keep a Windows install just for this.
> for AMD since they do not have to supply as much voltage to their chips
... unless you're using EXPO/XMP. I would really recommend people who run automatically overclocked memory taking a closer look at how much voltage the motherboard is pushing into your CPU, especially into the SoC. Some motherboards just push the voltages to the absolute permitted maximum; ASUS is particularly bad at this. I run lower RAM frequencies than my system is capable of because I haven't seen much performance improvement above 5600 "MHz", and it can be made to run at almost stock voltages.
It definitely causes faster silicon degradation; the question is how fast it will kill the processor. Both Intel and AMD have shown us that it can happen very quickly, not in the course of several decades as we've assumed for the longest time.
