Specifically, will there be any instability or other problems if I install DDR3 1066MHz (PC3-8500) RAM with a motherboard rated to be compatible with DDR3 1600MHz (PC3-12800) & DDR3 1866MHz (PC3-14900), using Crucial's system scanner.
The machine came with a single 2GB 1600MHz stick. I had 2x 2GB 1066MHz sticks lying around, so I was wondering whether I could use them.
I tried searching, and only found answers for the other way round (RAM faster than motherboard specification).