I have an RME UFX, ASIO Fireface set as master device.  The Generic driver is greyed out an unselected. 
 
However, whenever I change audio settings, a popup appears that says "Generic ASIO Low Latency Driver" and in the box "Checking RME . . . "
 
Leads me to believe Sonar is using a generic asio driver.  WTF.  Seriously.  RME has the best drivers in the business and Sonar is forcing to use the generic?  Latency performance seems relatively poor.
 
If it IS using the RME drivers, how can I get SONAR to stop displaying the pop up?

I think this is something to do with your configuration.
 
This is what mine looks like for my UFX:
 

I have the RME unit and I have come across the problem you describe. I was able to chase it down to a MIDI device (Fishman Triple Play) in standalone mode. However I don't believe I ever came across it while utilizing the device while I was in Sonar. As Karhide mentions make sure your preferences are set.
 
And make sure that your MOBOs sound card is configured correctly. On my DAW that item is disabled, disconnected and dissed permanently.
 
Hope you get it figured. Regards,

More than likely Sonar is not forcing anything. Odds are you have a configuration issue or the RME driver is being hijacked by another process and unavailable.

I've just thought you might be class compliant mode. 
 
Check out this on the RME site: 
 
http://www.rme-audio.de/en_support_techinfo.php?page=content/support/en_support_techinfo_cc_mode
 
 

I think the above link is for the Fireface UCX, not the UFX. Apparently, the UFX will now do "Class Compliance Mode". I don't use that, so I don't know much about it, but I found this:
 
http://www.rme-audio.de/f../viewtopic.php?id=16845
 

As far as I know,there is no "Genetic ASIO" drivers. Only thing remotely generic asio is ASIO4ALL. And if Sonar were to use that driver, it would say ASIO4ALL.

genetic asio won't be available until 2023 ;-)

karhide
I think this is something to do with your configuration.
 
This is what mine looks like for my UFX:
 

My panel looks mostly like that except I am using the XLR pair 11/12 to my monitors, so 11 is set as the master (odd that it only shows the first of the stereo pair).

dubdisciple
More than likely Sonar is not forcing anything. Odds are you have a configuration issue or the RME driver is being hijacked by another process and unavailable.

UFX is multi client, and is most sophisticated interface you can buy.  Never before had problems.  But nothing else is open atm.