Arrrgh, - I removed the ASIO4ALL and employed the latest drivers for the sound card itself.  ASIO4ALL performed much better.   I tried the ASIO buffers in all positions but it was clicking and popping like mad.
 
I've only got 5 tracks down (MOTU symphonics and Ethnos).  Also, I checked my CPU load and 01 02 03 04 are not getting too stressed at any time.  RAM - only half is being used. 
 
Is there something apart from buffer settings I am missing here?  I should not be popping and clicking that much.
(btw, I am using the Focusrite 2i4 for a few weeks.  I also still have my UA1EX)

 

 
 

Wait a minute, I just learned that I should "unpark" some of my CPUs!   How did I not know about that earlier?  It seems to be performing better.   My laptop has not been running at full steam.   
Maybe I should start to freeze some tracks too...

If you've got wireless networking, go into Windows Control Panel/device manager, right click on it and disable it before running Sonar. You can enable it again when finished with Sonar. If there are any HDMI audio devices/drivers in there, disable them as well.

Windows wireless networking (more accurately the driver) has a habit of grabbing the PCI bus (through which pretty much all data goes one way or another) for long enough for the ASIO audio buffer to overflow. This then causes pops and dropouts. Under "normal" computer use, even games playing, this is unoticeable. Unfortunately it is noticable when working with near-real time audio and video.

This isn't just a Sonar issue by the way, it's a Windows one.

If you've access to the full BIOS (not all laptops give you that) it can be worth shutting off some of the cpu sleep/power saving modes as well because they reduce cpu speed when the PC thinks full throttle isn't needed. Trouble is DAWs go from low to hi cpu usage very quickly and the PC can be too slow to keep up. Searching this forum should find the relevant stuff.

tlw
If you've got wireless networking, go into Windows Control Panel/device manager, right click on it and disable it before running Sonar. You can enable it again when finished with Sonar. If there are any HDMI audio devices/drivers in there, disable them as well.

Thats excellent advice, - I didn't know about wireless and the bus usage.
I can get access to the power [saving] settings in the control panel, - are you talking about something deeper than that (like when the computer boots up, you can go into a DOS BIOS screen) ?
I'm getting a desktop soon God willing, a core i7 Lenovo Thinkserver.  That should beef things up somewhat.
 

A new PC won't remove the Windows-created issues, wi-fi, cpu parking etc. will still be there causing the same problems. A faster/better cpu can certainly help reduce latency because it can process data faster, but it is still at the mercy of hardware drivers and Windows itself. Lots of audio issues with PCs sadly aren't always fixed by throwing more cpu power at them, assuming the current cpu isn't running out of breath.

The basic problem is that Windows was never designed as a "real-time" operating system that can dedicate all its attention to one thing all the time. It's a multi-tasking system that continually shifts its attention from one thing to another, balancing all the various demands in a way that's hopefully not a hindrance to the user.

The audio buffer setting in DAWs/interface drivers tells the audio driver how far ahead it should be looking when processing audio. Hopefully when Windows looks away there"ll be enough data in that buffer to keep things going until Windows decides its the DAW's turn for some attention again. If the buffer is too small then it empties and it's pops and dropouts.

Tuning a DAW PC is about making sure Windows and the hardware have the best chance to get their full attention back to audio processing in the minimum possible time so we can then reduce the ASIO buffer size and so reduce latency.

As for BIOS, it isn't a DOS function, it's the very basic, initial hardware settings that essentially tell the computer how to handle the hardware. How many volts to use for the RAM, cpu clock timings etc. It's accessed immediately on boot before Windows starts to load. How you get into it varies from motherboard to motherboard and many laptops don't even let you into most of the more complicated settings.

The cpu power-reduction settings are usually called C0 to C3, but may go up to C10. Also S0 to S5. To be honest, unless you are comfortable that you understand what the BIOS does and are confident about changing settings that can make a big difference to the PC and restoring the manufacturer's settings if things go wrong, you're probably best leaving them alone except as a last resort.

tlw
The basic problem is that Windows was never designed as a "real-time" operating system that can dedicate all its attention to one thing all the time. It's a multi-tasking system that continually shifts its attention from one thing to another, balancing all the various demands in a way that's hopefully not a hindrance to the user.

I am quite familiar with BIOS.  Even flashed a few in my time, but in the past 5 years I've lost touch a bit.
A lot of people on this forum including yourself seem to have stuck with PCs as a system for your DAWS.  But I guess MAC is not quite worth spending all that extra.  I guess MACs and PCs multitask equally, unless the MAC has a way of giving one application absolute priority over the CPU. 
 
I've unparked my CPUs and its performing better (two were parked).  I'll disable the Wifi and try and close down other things.  How about a solid state drive?   If Windows is executing other stuff, a major bottleneck would be if the other processes had to access the HDD.  

Actually the PC that runs Sonar is the only Windows machine we have. The rest are Macs and an old PC running Linux. And the Sonar PC is getting rather unreliable. I guess at some point I'll have to make a decision whether to replace it or go 100% Apple. Trouble is while I prefer OS X (or any flavour of Unix) to Windows, I prefer Sonar to Logic Pro. I've been using Logic quite a bit over the last few months because I'm doing stuff with people who use it and it made most sense for me to conform to them than them all buying PCs and learning Sonar.

As for the Apple vs Windows religious argument, not something that bothers me. Both have strengths and weaknesses and it's Windows running on countless (relatively) cheap PCs that built the personal computer revolution of the last 25 years.

As systems for DAWs it has to be said Apple have a huge edge in one regard. Their Core Audio/Core MIDI system works exactly as described. Just load whatever driver is needed and that's it. No need to mess with a registry, switch core cpu functions on or off, wireless networking and bluetooth work seamlessly with very low latency audio and MIDI. There's even low-latency wireless MIDI built in as a function of the operating system. BIOS. What BIOS? It "just works" as they say. There's reasons other than Apple's advertising and "everyone else has got one" why if you see a computer on stage 95+ times out of 100 it has a glowing whitelogo advertising its presence.

Retina screens are fantastic compared to the usual 1900x1080 HD PC monitor and Apple's engineering is good.

And behind the slick graphical interface there's a full-blown multi-user GNU/Unix system complete with terminal shells, X-Windows, everything.

Downsides? Few good games for a start, in fact less software generally. Then there's the cost of a decently specced i5 or i7 Mac in the first place, and the hardware spec is always a bit back from the cutting edge as far as cpu speeds go. No way to update modern Mac hardware, not even to just add RAM but perhaps that's not the problem it used to be when a big leap forward in computing power (and software requirements) happened every 12 months or less. Only way to plug in additional stuff is USB3 or, for things that uses the PCI bus like non-USB "full speed" SATA drives or UAD's cards is via Thunderbolt, and anything with "Thunderbolt" written on it is expensive.

Anyway.

An SSD as system drive (Windows+Applications) does make things feel and load much snappier, PC in my sig goes from off to Windows logon screen in under 20 seconds, desktop 5-10 seconds after that. After that, where data drives are concerned opinions vary. I use one SSD to spool audio to, works at least as well as the RAID 0 array of two 7200rpm HDDs I used before, uses less power and is silent. Which helps keep noise down. Some who use big sample libraries such as the orchestral collections rate highly dedicating one to the samples.

PCs can and do make perfectly good DAWs and it's easily possible to build one yourself with more brute power than most Macs for less money. On the other hand it means beating Windows, an operating system built for office applications and games, into doing something MS haven't historically paid as much attention to as Apple have. Though Windows from Vista on has been getting better for our purposes as MS have gradually introduced some stuff such as giving an application that says it's "professional audio" more priority.

Cakewalk have had a long relationship with MS, which might be why I find Sonar the best of the Windows DAWs. That and included plugins which are superb - much better than most that come with Logic for example.