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 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.
I dont think you will void your warranty if you change the setting to have the motherboard run at with a higher speed ram setting.
the 1600mhz is the highest speed ram the board would handle, and since the cost of ram varies per maker and speed. It would be ridicoulous for them to lock the motherboard to run at that speed from start as not everyone may fork out for that speed of ram or might be able to put it at a good use for that matter.
just look up as how to enter your bios and actually set up the memory timing speeds manually that way you will be able to get the board running with in the specs you are looking for.
youtube has alot of videos on this board check some of them out, i think even tiger direct did a video with intel showing some of the features and setting the bios of this mother board has.
The processor which you are using here will support only up to 1066 MHz memory. Here in this system processor is the one which controlling memroy. DX58SO motherboard will support 1600 MHz memory, you need to use 1600 MHz memory supported processor to enable the same.
You can chnage the memory speed from BIOS to work on 1600 MHz, however its not recomended - To do the same you need to chyange the memory multiplyer to 12 from BIOS Perfomance menu..