pxa 255 400MHz

Hi
I am currently running our pxa255 based hardware at 331.8 MHz, the hardware
runs with problem and power on and off work without any problems.
I tried to crank up the speed to 398.1 MHz following the data *** spec.
the hardware run fine but does not shut down correctly and crashes horribly.

I have double checked the registers clock register and memory setup
registers, has anyone else had this running at 400 MHz

Regards


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