This whizzing sound is killing me, and the CPU meters are jumping.
 
When I start up X2 the CPU meters go back down and that buzzing sound disappears. What could be causing this in X3b?

Are you opening an existing X2 project or a new one started in X3?

Bibs

Do you have Melodyne Essential on a track. There is a know issue with it causing buzzing. Just a guess.

If you bypass all FX does the sound stop?
Can you isolate it to a single track or bus?
Is input echo on?
What are the internal routings on your interface?
 
Also, some of us have experienced a buzz sound from the tape sim if we leave our PCs on and inactive for hours on end right around 60 hZ. Is that it?

Hey thanks guys for all the help you provided.
 
I did manage to solve most of the problem in Preferences, the "Route All Audio Thru Fx" box was checked and that left open loud Fx channels to route audio thru but brings in extra noise.
 
X2 didn't have this option, and X2 still is just a small tad bit quieter. 
 
@wizard 71, I did open X2 projects, and new X3 projects, but did cut a lot of noise by disabling the Route thru Fx option.
@mosvalve, no Melodyne yet.
 
@gswiz, couldn't find the bypass all Fx switch.  Input echo was off, cutting them all on brings in the noise in X3, doesn't do that in X2 though. In X2 you could cut all the input echo switches on and still get no noise. The Tape sim wasn't on, but I did get it basically sorted out in preferences.
 
Thanks again for all the help. 

The letter E toggles the all FX on / off setting on the control bar. Or the button on the control bar will do it. It says FX surprisingly enough. ;-)

"Always stream audio through fx" was just a name change from "play effect tails after stopping" with slight modifications to account for vst3 fx and audio handling.  
http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X3&Lang=EN&Req=NewFeatures.24.html