To improve recognition on boot I would set the 'Interface format' directly at the UFX+ from Auto to TB.

I am pretty sure none of the BIOS settings could change performance. Simply set them to default.

The main difference between USB and TB comes at higher system load - many channels and plug-ins. Then TB should be able to reach a lower latency (usually one buffer size less).

As far as I remember I didn't change anything else apart from turning TB on in bios.

Unfortunately this unit is also used for location recording on a laptop with USB3 and I need it to connect automatically to whatever I plug it in.

Higher system load for what? USB or TB? It's not clear to me the way you put it.

I just installed the Intel Thunderbolt drivers from the ASUS mobo support site and now I have this small blue TB icon in the task tray. Is this what you're referring to?

> Higher system load for what? USB or TB? It's not clear to me the way you put it.

ASIO buffer size can not be 32 buffers for all types of project.
If you use a higher sample rate you need bigger buffers.
If your CPU is under stress (by big project or one with CPU hungry VSTs) you also need bigger buffers.

All is about whether the CPU does it get managed to perform the i/o tasks in time.

For this reason many people tune their PC so that the CPU cores are not doing useless stuff.
This gives the CPU cores more headroom to be able to process all in time without audio loss.

The USB protocol usually is know to have more overhead compared to PCIe.

So if you have a high Project / CPU load on your system then it it could be,
that you require with thunderbolt only an ASIO buffersize of 128 buffers,
where you might require with USB3 maybe 256 ASIO buffers.

Thunderbolt has PCIe speed.

From the pure latency values between USB3 and Thunderbolt you dont see significant latency difference.
But under a heavily loaded systems its much likely (never tested it on my own), that Thunderbolt
works more efficient so that you can works potentially with lower ASIO buffer sizes.

And if you can use lower ASIO buffer sizes, then you have less latency end-to-end between
Recording interface and DAW on your PC ...

In such discussions btw always carefull .. LatencyMOn i.e. measures another latency than
the latency which is being reported by the RME driver to Cubase.

There is also a latency inside of Windows inside of the kernel, how agile the CPU can react / work
on the processes and threads. If there are i.e. drivers that occupy the CPU for too long and if
on this core/thread also an audio process is running, then this narrows the ability of the CPU
to process audio in time (without loss, clicks, pops), especially if the system is under stress.
This you can only resolve by tuning your system and by using higher ASIO buffer sizes.

And thunderbolt shall have the benefit - as it equal PCIe performance - to perform better
in higher load szenarios compared to USB. Although I could not see this big difference in my projects.

You can isolate if it is the Fireface or the computer causing this by leaving the power on the Fireface and removing power from the computer. If it then is recognised it is the computer that needs the full shutdown. If it is still not recognised it is the fireface that is left in a strange state after the shut down.

Good work!  So both seem to be in a state they can't get out of.  Is this solution ok for you?