So apparently I completely missed this news for over a week. It's probably something that our readers would like to know, though, because it affects the stability of GTX 1070 cards. Video RAM chips are purchased from a variety of vendors, and they should ideally be interchangeable. It turns out that, while NVIDIA seems to ship their cards with Samsung memory, some partners have switched to Micron GDDR5 modules.
According to DigitalTrends, the original VBIOS installed in graphics cards cannot provide enough voltage for Micron quick enough, so it would improperly store data. This reminds me when I had a 7900 GT, which apparently had issues with the voltage regulators feeding the VRAM, leading to interesting failures when the card got hot, like random red, green, and blue dots scattered across the screen, even during POST.
Anywho, AIB vendors have been releasing updated VBIOSes through their websites. DigitalTrends listed EVGA, Gainward, and Palit, but progress has been made since then. I've found updates at ASUS that were released a couple of days ago, which claim to fix Micron memory stability, but it looks like Gigabyte and MSI are still MIA. The best idea is to run GPU-Z and, if Micron produces your GDDR5 memory, check your vendor's website for a new VBIOS.
It's a pain, but this sort of issue goes beyond driver updates.