USB is one of the items which exist even in the boot chain. Boot can fail for a number of reasons, such as:
- Power issues. USB does draw power. Power supplies fail over time, e.g., electroytic capacitors can fail.
- Drivers exist for USB within the boot chain. A bad driver can do this, though it is unlikely.
- The BIOS provides an environment for all boot software, and sets up things like power rails and clocks. If the BIOS corrupts in any way, then interactions with that BIOS can be a problem.
- Extending on the BIOS, UEFI typically allows or requires the o/s bootloader software to install their own drivers. So it is possible that a driver which is failing under UEFI might be from an o/s update, and not necessarily part of the BIOS.
Do you have a
powered USB HUB? If you plug that in to the front USB port, and nothing else, and it boots, then try plugging in an
unpowered USB HUB with nothing plugged into that. A regular HUB will draw power, but not a lot. If the unpowered HUB fails, then it is more likely a software issue. If the powered HUB works, but not unpowered, then likely there is a power issue. An unpowered HUB, if it works, could then have something plugged into that, e.g., a keyboard, to add a bit of power draw. Incidentally, if the items plugged in to the front are removed, and then placed somewhere else, e.g., a back panel USB connector, does it fix the problem?
One reason why a BIOS can corrupt is if the battery is low and power is completely off such that memory for settings depend on that battery. This would be a "brown out" for the BIOS, which is more dangerous than a complete loss of power since it means it only appears to operate normally, but bits are on occasion going to not copy correctly. Replacing the battery (if it is old), and then doing the BIOS reset procedure (usually removing the battery, shorting two pins for 10 seconds or so, and then adding the battery back) can fix this (at least temporarily until the batter is needed again; this is why a new battery is useful even if it isn't old).
Lastly, if all of that is inconclusive, you could check for a BIOS update. Just make sure you perform any BIOS update without extra items plugged in.
Then of course there are all of the other mentioned possibilities, e.g., a cable can be a problem because they do receive some fan vibration, and there is thermal creep (cycles of heating/cooling loosen connectors over many years). So it could be any of those issues. I doubt the power supply is the issue, but if it is old and electrolytic capacitors are failing, then the USB devices on that power rail might be "the straw that broke the camel's back" (I always wonder why one would put a camel's back in a computer).