Odd results on a dual raptor raid0 bench

[Sarkster]

Im informed by a mate that you lot here are the knowledge in matters of the PC.

I benched my raptor 36gb raid0 setup with the latest Sandra and it gives decent results except for a severe dip in performance at 40% into the drive.

I defragged, moved the pagefile to another physical disc, still the same results. Anyone got any suggestions?

Thanks in Advance.