At work i got my hands on a neo2 for overclocking purposes..
1) turn off both sata controllers in the bios.. I remember something about the controllers screwing up the overclocking process.
2) the neo 2 does 227mhz max. No higher unless multiplier is unlocked.
infact, you should be able to do 227 out of the box, someone said that it may be the cpu... I was using the winchester, one would think that the newcastle would be able to do it.
Try cranking the voltage up to like 1.5-1.75 and give the memory voltage a little boost too. If you're still not having any luck, go buy a winchester =p