promidi
I personally would not be using the registry to disable core parking.

I use a utility called ParkControl from https://bitsum.com/parkcontrol/

Windows Power Options - change plan settings - advanced - Processor power management. Set min and max processor state to 100%. Done.

Glad Alex chimed in with that , say what you will but nobody should have to go into a registry just to record a song on a DAW.  
And that RAM could be causing an issue, not sure but I was always told to use nothing but matched sets. 
That is why your number is oddball. . To bad you just missed all the sales. Might still be New years deals at New Egg. 
If your flush for money t's worth it to have good RAM  two sticks of 8 or four stick of 4 is standard.
If your hard up best you can do is try and match another stick of 4 to that.  As said, buy in matched pairs and even better all 4 matched. 

Hi, promidi, the utility https://bitsum.com/parkcontrol/  will not launch on my computer. It downloads just fine but will not open.
Thanks Cakealexshere, I changed these settings a few days ago to the 100% value

Rick Ranum
Hi, promidi, the utility https://bitsum.com/parkcontrol/  will not launch on my computer. It downloads just fine but will not open.

When you run ParkControl, it places an icon in the system tray.  You can then open it from there.

Have you run LatencyMon to check DPC latency?
 
Constant dropouts mean that some process is interfering with your audio driver's ability to pump data out to the interface. Did this problem just start happening recently, or did it coincide with installation of new hardware or software? If it was working yesterday, or last week, then something has changed and the challenge is to figure out what. It could be broken hardware (e.g. a bad NIC) but more likely it's a background process or interrupt handler. LatencyMon can help you zero in on who the culprit is.
 
If LatencyMon says all's well, next look at processors running within SONAR (meaning: plugins). Is this problem specific to one project? If so, what's different about that project, e.g. new plugins? Does the problem go away if you open SONAR in safe mode (hold SHIFT key down while starting)?

promidi
When you run ParkControl, it places an icon in the system tray.  You can then open it from there.

Check my earlier post .. you can turn off core parking easily via windows interface nowadays no need to install a utility.

If that utility is constantly running in the system tray I would uninstall it. Cheers.

Actually I would remove it anyway. The link you supplied threw me to a website with a virus.

I note the utility has a lot of bogus vapourware features or stuff already built in windows. Sorry.

KEY FEATURES:

CPU Control. Ability to tweak, unhide, and control CPU core parking and frequency scaling without reboots!
Bitsum Highest Performance. Create a power plan that auto-optimizes your hardware for max performance far beyond the system default ‘High Performance’ power plan.
Bitsum Dynamic Boost*. Auto-switch power plans when your PC goes active or idle. Stay running in Bitsum Highest Performance Mode while using your PC.
Power Plan Change Notification – Shows you when your active power scheme changes and what process initiated the change.

How about my ram setup again. There are 3 sticks of 2gb and 3 sticks of 4gb totalling 18gb. Could this effect the performance of a project in sonar?

Hey allex good call- Probably why it won't open the OP anti virus was doing it's job. 
 
Did you catch BitFlippers post .. you said :
 "I have gone thru all the steps for optimizing window 10 to run smooth with sonar" 
So I assumed you had already run Latancy Monitor. 
 
Having matched sets RAM is what we call Best practise. It can cause a hit to performance etc. Not always but why take a chance, you can get lucky, but if your building a killer DAW machine you certainly don't scrounge around for any old sticks of RAM. You should even check your Mobo web site for a list of "approved and tested" RAM if you really want to get going on it. 
 

Rick Ranum
How about my ram setup again. There are 3 sticks of 2gb and 3 sticks of 4gb totalling 18gb. Could this effect the performance of a project in sonar?

"""!!YES!!"""" Never mix and match memory sticks for high performance, especially on a computer running memory and bandwidth intensive applications like SONAR!
 
Also that is a LOT of memory sticks, each one eats up about 1.5 volts = 9 volts just for memory alone so I hope you have a good size 400+ watts power supply to insure all components get the juice they need and when they need it. And that too could very well be the source of your problems. You should always MAX out the capacity of the memory slots before adding more sticks. Not only is that the shortest signal path, it uses the least amount of energy.
Maximum efficiency for 16 gigs of memory would be 2 x 8 gigs sticks = 3 volt draw
And ALWAYS use high quality, high performance tested memory by trusted vendors.
 If your motherboard is meant to run in duel or multiple channels, all memory sticks must be the exact speed and timing specs supported by your motherboard. If not you are you losing half the memory bandwidth, you motherboard has almost certainly defaulted by to the slowest memory speed the mobo supports. So if you have PC 1600 memory sticks installed and your mobo defaults to the minimum PC 1333 your configuration isn't efficient for maximum performance.
All Memory sticks must be equal values and correct speed for duel channel operation and they must not be installed right next to each other.
Your CPU's memory controllers and multipliers are designed to work in groups of "4", so when choosing how much memory to install, always make sure the total amount can be divided or multiplied evenly by 4 for maximum speed and efficiency.
For instance, for an 8 gig duel channel configuration, "pair" one 4 gig stick into slot "A" and the other into slot "C". For a 16 gig config. install another pair of 4 gig stick into slot "B" and the other into slot "D". DO NOT pair memory sticks right next to each other.
 This information should be detailed in you mobo's documentation.
 
A really good way to test for this issue is to pull all memory sticks out and pair two 4 gig sticks, preferably made by the same manufacture) insuring exact speed and timing specs supported by your motherboard.
Boot into BIOS and make sure duel channel is enabled, and your memory is running at correct speed.
 Some mobo's automatically detect and change these configurations some don't.
 8 gigs of memory is sufficient to run SONAR providing you don't have too many memory intensive plugins like VSTi samplers running.
 Setting the buffers on the 18i20 Gen 2 @ 128 should give you very smooth and stable operation with an effective latency @ 2.7 ms with SONAR set at 24 bit 48k/HZ.
 
And if my guess is correct (which is all any of us can do without actually being there), your clicks and pops shall be gone and your computer will run smoother and maybe even a tad faster on the 8 gigs than it does on 18 gigs for every day use.
 But of course "16" gigs is better sweet spot for hungry apps like DAW's when running at full speed and spec..