I have a bunch of low cost DDR3 sticks, most are 2048MB. I also have a pair of G,SKill DDR3-2133 which I bought back in 2013 for the M5A99FX PRO R2.0
i had 2 sticks of DDR3 in my tray, that RAM was crap and the M5A99FX kept crashing, sent the memory back but never got my money back from the US vendor
So I spend more $ and got the 4096MB sticks from G.Skill that work fine
Since then I have accumulated more DDR3, all 2048MB capacity, I have also spend a lot of time with close study of the problems
I have been working on this problem for a long time, it clear there is a flood of bad memory.