I'm honestly not too sure about your board. You could always just try using auto settings and see if you can get there. Believe it or not you can usually get a decent OC by letting the board deal with it. Guessing you're either hitting another big FSB hole around there or your board just doesn't like that high of a FSB. You can try just going to 1600mhz and if it that works. If not then it just might not happen. I know I can get 1600mhz FSB, but in no way is the computer stable.
If you're freezing in the BIOS then you are probably really unstable. Chances are you might need a decent amount more voltage to keep it stable. I know in that thread someone said they were running 1.5V HT. I'm guessing that is probably getting toward the high side, but might not be out of question. Have to maybe do a little more digging for 750i overclocking threads.
Here is a good little quote from someone
On a 8x multi you can go 50 safely 1333-1350-1400-1450-
And run at least a good 1-2hr cpu test of OCCT.... When it fails bump the voltage up a bit
Sorry for the long drawn out instructions, just felt we could use it here...
You might actually want to go back down a bit and make sure that you're completely stable before moving on. If you have been writing down numbers or saving settings you can default back to what you know works. Make sure that at 1550mhz you are completely stable, then try 1570mhz and play around with minor changes of the voltages to figure out which one it needs. The trick is to make small changes and creep your way up. Unfortunately it's also the worst part because it can be tedious and consume a lot of time.