I'm sure I'll get some comments through which I'll learn a great deal (as per usual) from smarter fellers and gals than me by posting this BUT...
 
I've been having a problem that cropped up as far back as X2 where my 8 core cpu seemed to only use the first core and it would max out rather quickly.  When I first got my machine from Jim (Studio Cat) it was a monster.  I could track, tweak and mix all without freezing many (or any) tracks and throw all the plugs I wanted into any project.  But then, I started getting pops and crackles after loading up a project with plugs and many tracks and started having to resort to freezing and upping my sample buffers when mixing on my interface (Motu Audio Express).  I could see every time this happened that the first core was maxing out in Sonar's cpu meters and that the other cores were barely registering.  Yesterday I was trying to mix a not inordinately large mix when I started getting pops and crackles.  So first, I froze most of the tracks.  Still no love.  So I raised my buffers to 1012.  All was good.  But it finally bothered me enough to start interweb sleuthing about those damn cores.  And I stumbled on Core Parking and how to disable it.  There were older threads from this forum as well that, as far as I could tell, never had a definitive answer as to whether this was good or bad...would work or wouldn't...should be done or never, ever, never do it no how, no way.  So I found this method:
 

Thanks for the info olpal. I've only got a quad core, so I need em all firing to get the most outta my DAW. I've noticed that my first core gets the biggest workout too. I'm hoping this will help me as well.

I will try that see what happens. Thanks DogHouse.
 

You might consider creating a restore point before trying this. Registry stuff goes funny sometimes.
 
I tested the change on a particular project where I use Galbanum Piscis Rapture Pads that push the first processor.
 
After the change, I saw no improvement, so I reverted.

One anomaly I've noticed since making the change and listening back to several large projects is that sometimes the first core will "load up" as the song progresses. Not like it used to...but noticeably. If I stop playback at that point and start playback again it goes back down. Weird.

Yorolpal,
 
Some synths have very long 'impulses'. Are you using synths when you notice this?
 
It could be the case that when you have several minutes of held tones fed to a synth that you slowly grow the amount of load. If the synth can't spread that load across the processors, it'll stack up on one (probably the first). For things like insert fx, you will probably not have this type of problem because the relatively small amount of work can be moved to a number of processors.
 
For me, I notice the issue significantly with Galbanum Piscus Pads when I stand on the hold pedal on my midi device. I almost never have the problem otherwise.

I made the reg change and my resource monitor still shows 4 of the Cores parked
Do you see the resource monitor change ?
 
JR

FYI - Alternate ways here also:

http://forum.cakewalk.com...n-It-OFF-m1861804.aspx

Not sure this is the thread but another forum member posted this website and core parking utility:

http://www.coderbag.com/p...u-core-parking-utility

I have done neither so proceed at your own risk.

Definetely a must do tweak for Windows 7. I would get crackles during playback without this.
I found with Windows 8 it works acceptably without the tweak.

What I don't get is that you bought a custom DAW computer and still had to tweak it. Doesn't Jim offer excellent support ?  I have heard so from most folks? 
 
Also I could be wrong but I think you need to back up the registry using a different tool than system restore. 
I use CCleaner and it has a registry cleaning tool that always gives you the option of a registry back up before you nuke stuff.