And so i reduced the clock to 66 MHz...and everything works fine now! At 90 MHz the error still occure.
But i really don't like this solution- can another SDRAM work better (perhaps PC-133)??
Which SDRAM (and CT60 clock) do you use?
This isn't necessarily SDRAM issue, it can be cache issue inside the CPU for example. As Alan said, this is how it is. Remember CT60 was projected / tested / developed for 66 MHz, everything above is just a bonus. You might want to try to play with higher values (some people have reported 75 MHz as their working frontier) but you know, better 100% working 66 MHz than maybe-something-silently-not-working XX MHz ;-) 66 MHz was widely accepted as standard setup, i.e. all demos/intros are optimized for 66 MHz anyway.