I’m sure it was running at 1066MHz and 533DDR originally, the other RB1100AHx2 I have still is (both running the latest ROS 5.14 and firmware 2.39).
None of the change-frequency choices are supported. Reboot doesn’t change anything. Has anyone else seen this?
Your best bet is to send a support output file to Mikrotik.
You can try to reboot the router with serial console cable and set the CPU speed in the boot loader options.
A little more intrusive option is backing up the config using export, do netinstall not saving config, set cpu speed, and put the config back on making sure not to paste line with CPU speed setting.
Change-frequency is not going to work, this feature was designed for RB5xx. It does not work on any modern board.
Change-frequency will be removed at the next RouterOS version. Thank you very much for the report.
Use Nathan suggestion to change frequency on any modern RouterBOARD,
[admin@MikroTik] > /system routerboard settings set cpu-frequency=
However another issue remains, how you got 533MHz as your CPU frequency. Do the following,
set regular CPU frequency back on your router;
make one support output file and name it supout_normal_frequency;
if you notice that frequency is downgraded again, make another file and name it supout_low_frequency.
Send both files to us for further investigation (support@mikrotik.com).