I needed to transfer about 1TB of videos between two external HDD drives with USB 3 interface (blue USB connector)
My new computer has on the rear of the motherboard (according to the MB user guide) four USB 3.2 Gen 1 ports with blue colours and two USB 3.2 Gen 2 (with green colour)
The green connectors are supposed to be faster than the blue and are are backward compatible.
But when I connected the two HDD's to these connectors, the transfer rate was miserably slow and it would take 1 day to complete the transfer.
I shut down the PC, connected the HDD cables to two adjacent pair of USB blue connectors and the transfer rate is now what I expected fluctuating between 30MB/s to 90MB/s and it should finish the transfer in about 3-4 hours.
I also disconnected all other external HDD's and in both cases I had only the two specific HDD drives.

My question is why the green coloured ports were so slow?