No, if your RAM is 1600, and you set it to 1600, you should get 1600. Even though AMD supports 1333 natively, it'll still work with other speeds. From what I understand it just really likes 1333. So if there's an option to change the multiplier in your BIOS (I have NO idea why you're motherboard would lock the multiplier) whatever you set it to, is what you'll get out of it, assuming the board and the RAM can take the speeds. The RAM can take the speeds, because it's rated for it, and I haven't seen a board that doesn't support 1600 MHz in a pretty long while. Good luck!