Hi
The Nvidia GeForce GTX 1070 comes with 8GB of GDDR5 memory. However, due to demand, industry supply chains, and other manufacturing considerations, many AIC partners have dual sourced memory chips from both Samsung and Micron. Unfortunately there is a difference which may have been proving both puzzling and irksome to owners of this recent Pascal GPU based graphics card. According to reports, owners of GTX 1070 cards with Micron VRAM may experience "flickering and poor memory overclocking results".
See the link:
http://hexus.net/tech/news/graphics/98335-nvidia-geforce-gtx-1070-bios-updates-fix-memory-issues/Is this problem will be solved in next bios update?