Fbarberis, would you please share with us your system configuration?
We are still thinking that this is a lack of power issue. There are many hard drives involved and it may require at least an 800W power supply.
I have dq77mk board and I have the same issue. mine doesn't reboot tho it just stays on the first screen without any options to go to bios. I believe its the motherboard but would like it comfirmed before I buy a different brand motherboard. mine happens on usb 2 and 3. I tried usb legacy and boot order options but none of the recommended fixes work that iv found from google searching.
For what it's worth, I've seen this behaviour on a specific Toshiba notebook but it only happened with USB Western Digital HDD's, WD drive caddies seem to have an odd firmware compared to other manufactures. I believe the UEFI firmware was trying to boot from the WD or at least initialize the partition table during POST, and hung indefinitely.
The fix was an updated BIOS ROM for the notebook.