I have a Mikrotik Cloud Core Router CCR-1036-12G-4S running RouterOS 6.15 and using 3.10 Firmware. I have noticed a bizarre issue with the SFP LEDs and the Fan Noise.
Firstly, all of the LEDs flash next to the SFP Ports even though only one SFP is actually connected (a Mikrotik Direct Attach cable in this case).
What’s even more bizarre is that the Fans noise appears to change in time with the LEDs flashing on the SFP Ports. I’ve uploaded a video to YouTube that tries to capture this strange phenomenon.
Ideally you need headphones and you do have to turn them up but I’m sure that I’m not going mad!