Hi SDH,
Thank you very much for sharing your experience.
My point was to 1600MHz modules just financial, I found local offer with a very good price for this modules.
Seller have exactly six eight gigabyte modules and I don't think I may need more in upcoming future.
As I understand this, it should theoretically work since HMT31GR7EFR4C-PB will work on 1333 MHz instead of 1600MHz.