I am using corsair vengeance ddr3 ram, and Gigabyte z97x sli-cf motherboard on Win 10. unplugging and pluggin the ram back in temporarily fixes the problem. it will register up to 11.9 gb in available memory, but it doesnt last and later that night it will be back down to 7, now its the lowest its ever been at 4. I have already tried selecting maximum memory in system configuration, it does nothing.