Yes , seems to be strange,
Which drivers are you using  for the RME soundcard ?
Do you use  other soundcards ?
32 or/and 64 bit Win and Sonar?
 
 

64 Win 10 with rme 6952, which has drivers dated 9/24/2015.  BTW if you don't want your gear to go obsolete buy RME (just an aside), they have developed drivers for this for like 10 years now.  I do keep my Realtek onboard soundcard enabled for listening to internet stuff.  Never had a problem before though.

This has really flummoxed me.  The latency and clicking and popping is really bad on my old projects.  They were fine with the Athlon X2 260.  I went from there to a Phenom X4 970.  Totally gobsmacked!  Even with a 512 cache there's clicking and popping.  I wonder if it's the virtual instruments and not sonar.

Did you really just change the CPU in an existing computer, and leave everything else unchanged, or is this a new physical machine?

This might belong in Computers as it's smelling like a configuration issue, not Sonar. You should not have click and pops in this day and age. RME driver are the best and you should be able to run at low settings. Something is wrong. 
Many things cuase issues with building your own computer. 
The rules seem to make sure every detail is up to date, Bios, MoBo drivers, Video drivers, etc. 
SOmetimes HDMI audio drivers cause issues,, the list is long and easily googled.
That's why I said to run latency monitor as it normally tells you whats wrong. 

True Cactus, it MIGHT, maybe a moderator should judge! Kyl:  that's what I did, just dropped the cpu in and turned it back on.

So, I guess it's just my old projects that are affected.  I can record with no problem.  Oh, well if anyone has any ideas that'd be great otherwise I'll move on.  I ran Sonar with latency monitor on and it had lots of page faults, but I really don't know what's causing it.  So now I've narrowed it down to just KONTAKT doing it.  ...and I don't mean area 51! :). Thanks for your hq iq.