Had the same experience overclocking old AMD Phenom II a while ago. Worked flawlessly in all publicly available test software I tried, until I run some custom heavily vectorized code, which eventually required to shave off almost all overclocking :D
There's a way (at least on my Intel) to tell the processor to clock down a certain number of steps depending on whether AVX is being executed. So, for the majority of stuff that didn't use AVX I let 'er rip, but when AVX is running it clocks down a couple steps. I could use less voltage, and this CPU is fast enough. I think it's a 13900k.
