Stable settings Gigabyte GA-X58A-UD3R KHX1600C8D3K3/6GX i7-920

I want this rig to be stable for video editing and encoding. I heard that my mob does does not support 1600mhz, and when I try to set the bios to this it hangs. I am new to this so I am wondering why the mob supports 1066, 1333 and 2000 but not 1600. Anyway, I would like to set the RAM to 1333, but I am wondering what timings to use. The Kingston memory is rated at 1600 8-8-8-24 1.65 volts. Do I need to change these timings when I lower the speed to 1333?
Thanks in advance

That board supports up to DDR3 2100+ memory, which includes DDR3-1600. The SPD timings for that RAM at DDR3-1333 are 9-9-9 at 1.5V (JEDEC standard latency), but that doesn't mean they won't run at that frequency w/ tighter timings and higher Vdimm. SPD Vdimm at DDR3-1600 is 1.65V, so you can run it up to that voltage and still be within Kingston's spec's. Try enabling Extreme Memory Profile (X.M.P), or w/ the System Memory Multiplier (SPD) at 10 (w/ a default BCLK of 133MHz) and Memory Frequency(Mhz) set to DDR3-1333 (w/ DRAM Timing Selectable (SPD)) set to Auto.

I tried enabling XMP but the system would either not boot or would keep crashing.
I will try again. Also, doesn't the speed of the memory also depend on the CPU? I have a i7 920 running at 2.66GHz

The DRAM frequency is dependent on the results of a given FSB : DRAM ratio. For example at a default BCLK of 133MHz using the 2:12 ratio (System Memory Multiplier of 12), the resultant / effective DRAM frequency would be 1600MHz. You can manually adjust the multiplier to 12, along w/ the four primary timings to 8-8-8-24 and DRAM voltage to 1.65V. You might also need to adjust the QPI/VTT Voltage from the default of 1.150V to around 1.3 - 1.35V in order to reach a DRAM frequency of 1600MHz.

Thanks for the help.
One other question. If I set the memory speed manually, is there any point in enabling XMP? Before when i enabled it, the system would not boot.

I would try setting everything manually first, then try and figure out why it's not POSTing w/ one of the XMP profiles selected.