DDR3 memory cannot run at 531 MHz frequency at the DM 816x board

Hello.

first i tried to the DDR3 Initialization with SW Leveling.

and I changed the DM8168's clock from 796Mhz to 531MHz.

but DM8168 board does not work at all.

Please advise what considerations to change the clock from 796MHz to 531 MHz in boot code.

Thanks in advance.

Regards

TCKwon.