Radeon gfx woes ruining my Sonar experience

So for a while I've been suffering from some horrible pops and clicks during playback in Sonar. Mostly when playing back VST synths. I have to keep my buffers at 512 samples minimum, even with all FX bypassed and the performance module showing quite light activity on the cores. 
 
This only happens during playback. I can play the synth in real time via my MIDI keyboard without clicks or pops, even CPU hungry synths like Monark and even at very low buffer settings like 64 or 96 samples. As soon as I hit play and Sonar tries to play some MIDI parts, pop city. 
 
Someone suggested to me that it might be a graphics card issue and to initiate conservation mode during playback. I did that, and lo and behold the clicks stopped almost completely, but sometimes made themselves heard during the display update. So there it is - a graphics issue. My card is a Radeon HD 7700. Not a high end gaming card by any standards, but should be more than enough to handle basic graphics functions. I'm not a gamer so have never put it through its paces properly, but just out of curiosity I ran 3DMark to see how it fared. The results were pretty atrocious - I got a graphics score of 527 (which put me below what you'd expect from a notebook with integrated gfx, according to 3D Mark). The frame rate throughout the test was a horrible 3-4 fps. Looking at the activity meters in the Radeon settings utility during the test, I saw that the GPU was pegged at 800MHz (the default for this card), activity at 99% and a temperature of around 50 degrees. 
 
If I disable the card in the Device Driver and use the onboard gfx, the clicks and pops in Sonar go away. So obviously my card is not working properly and I don't know whether it's a setup problem or whether I have a bad card. Have no idea where to go from here. My Radeon drivers are fully up to date. I also tried rolling back to an earlier version, but no difference ensued. I've done a completely clean install of the drivers (after using a driver cleaning utility). I didn't expect that would make a difference but I tried it anyway. It didn't. 
 
So what do you think? Does it sound like I have a faulty card, or maybe that it's not installed properly or something? Or perhaps there's some setting in the BIOS? I have a Gigabyte motherboard. I've had a look around the BIOS but can't see anything that pertains to my card. I really don't know what to do short of disabling the card altogether, but that's not a long term solution because I do occasionally use Illustrator and Premiere and would like a good working card for those.

To a large degree, it has a lot to do with how your motherboard and the video card interact due to hardware interrupts. If there is another slot you can move the video card to, you should try that. On the other hand, if your problems go away when you disable the card, why not yank it? You shouldn't need anything more than onboard graphics for Sonar anyway...
 
Regards,
Dan

Yeah I may try reseating it. Like I said, I do have occasional need for apps like Premiere and Illustrator and so a decent card is a plus.

TheMaartian
I had an older Radeon on Win7 that started having memory failures. It was Bejeweled Twist that burned that sucker up. So, knucklehead me, I replaced it with a newer Radeon. Unfortunately, it wasn't new enough (early 2012) for ATI to bother updating the driver to Win10. I was having one or more BSODs per day. I've got a Gigabyte GeForce nVidia now that just flies. And it gets regular (almost monthly) driver updates.
 
One thing I'll suggest is that for driver installs, don't just accept the default install. You'll get all of the 3D and gaming junk that you don't (I assume) want or need. I install just the driver and the PhysX app; nothing else is required. ATI "driver" packages may be the same.
 
Of the several ATI video cards I've owned over the years, all of the ones with cooling fans seemed under-cooled, so the Gigabyte card I bought has two monsters. Better safe than sorry.
 

EDIT: I've had this card for about a year now, and I've not had a single issue with it under Win10, even the Anniversary Update. And I got it on Amazon for $140, with a $20 rebate. So, net $120.
 
My default audio i/f setting is 48K with a 128 sample buffer. No issues. No need to run with a 64 sample buffer.

 I have one too. The main reason for buying it was less power consumption.  I game on a 1366x768 TV. No reason for a better graphics card. 

Hi James,
 
You're welcome to give me a call this week.
There's got to be a particular reason this is happening.
It's not normal/expected behavior...

just guessing, but you might try to disable your hdmi/audio outputs on your graphics card in the device driver- even if you had them off previously, an update could re-enable them

Will do. Thanks Jim.