pieces of junk

I'm about to RMA my 4th stick of these, I bought 2 sticks in December 2014 and both failed memtest, I RMA'd both, and both replacements passed memtest out of the box but are now causing random system lockups, one of the sticks won't even get me to Windows at the rated speeds, and the other fails a memory-heavy stress test within about 10 minutes. they said the first two sticks I RMA'd passed their internal tests, whatever those are-- but I had to run memtest for about 2 hours to get the failures so maybe they just threw them in and only tested them for 5 minutes. Anyways, the last time I bought from PNY 12 years ago I had serious issues too so. I think I'm done with them