You're doing it wrong. The benchmark results appear so good because you're running the uncore (northbridge) around 3600 MHz or above. The real-time bandwidth is a lot lower than that, and since QPI data strap is lower than uncore, you could face stability issues.
QPI should be higher than uncore, and if that's impossible to achieve, at least try to obtain 1:1 ratio. Since you're running DDR 2400 and above, try to keep DDR voltage below 1.65v and QPI/VTT below 1.35v, as both are deadly to the CPU.
And don't forget to use HCI MemTest with no pagefile to test DDR stability. MemTest86 is bad for checking DDR overclock stability. Prime95 v26.6 custom 512K FFT test with 75% of RAM combined with LuxMark to test QPI and uncore stability.