@pakos96 attached to this message there is a script that does the trick to change the ddrbin frequency.
Can be used on the boot block device directly on the board, or on a file to modify a ddrbin binary or an armbian image before sdcard burn.
Usage and examples are in-built with the script, so launching it without arguments provides all the help that could be needed.
Some notes:
THIS IS AN EXPERT THING. If you're not an expert, do not do this; do not come here later sobbing you made a mistake, or you will receive more insults that will make you cry even more 🫣
always always always test the ddrbin frequency change on a system booting from sdcard
if there is a bootloader installed in eMMC, it has priority: changing the ddrbin on sdcard won't have any effect until you clean the eMMC (or the bootloader)
some boards (notably X88 Pro) do not like ddr frequencies above 330MHz: they won't boot
changing the ddrbin frequency of the bootloader in the eMMC is very dangerous! You may brick the board (only way out: maskrom via eMMC clock pin gating)
ddrbin-switch-freq.sh