You went for a Intel board which makes this hard because you need to change some settings in the BIOS to run the RAM at the speed it needs to be.
No PDF of the BIOS layout for me to tell you how to do that.
I have no problems making the changes in the BIOS, I just don't want to void the warranty. With the system specs of the board and memory it should be supported. Intel is likely playing the conservative settings card to avoid warranty problems.
If your going to give yourself red tape like that then theirs nothing you can do about it.
If your memory supports Intel's XMP profiles, it's easy. Go into the overclocking section of the bios and see if you can select XMP Profile 1 from a drop down menu. That will automatically set the memory's voltage and timing to allow 1600 speed. The DX58SO will, by design, boot first at the lower speed until you make that change.
That being said, every test of DDR3 memory speed I have seen shows no significant improvement in any program except memory bandwidth benchmarks, and your CPU temperature will increase because of the increased voltage needed to achieve the increased speed.
Here the board which you are using will support 1600 MHz memory, however to enable the same you need to use 1600 MHz memory supported processor.
in i7 series system, processor is the one which controlling memory not the board. If you are using a processor which support 1600 MHz memory you will able to enable 1600 MHz memory speed on this system.
You can also overclock the memory settings from BIOS perfomance menu, Go to memory configuration and change the memory multiplyer value to 12.
This is why i buy patriot memory, they have the best customer support ever.
this might help you out a bit as to how to go on changing your memory settings inside your bios.
you still need to know what your ram settings actually are
hope that helps you get going as to what you need to do in order to change the memory settings.