I’d say that is your issue right there.
Probably different speeds and you’re machine is being a bit fickle.
As a general rule, don’t mix RAM modules 
I personally avoid mixing brands too, though provided they run the same speed/size, it shouldn’t be a problem.
I run UE4 with the same CPU & GPU, only on an older motherboard, without BSOD issues.
All my ram is identical - same brand, speed, size.