So I ordered 5 GPUs from Newegg and they're all identical models and factory refurbs. I've tested them all, and they exhibit the same problem. They crash the entire system about 8 seconds in to 3Dmark Firestrike, and also in Overwatch on the main menu (except of one of them, which was able to make it into a match before crashing). I've tested on two different platforms (my main LGA 1150 system, and an old backup AM3), 3 different power supplies, and two different versions of Radeon drivers. The only thing I've found to keep it from crashing is to downclock the GPU by 30%. Then it can pass 3Dmark and run Overwatch.
It seems too much of a coincidence that I received 5 bad cards that made it past QA with the same problem but that's the conclusion I'm coming too. Is there anything I'm missing or should I just pack these up and send them back?