I've been having problems juggling latency and pops with 2 interfaces.  One is an ESI wamirack PCI 192x the other is a new usb behringer fca610. With either unit, with 6 soft synths and about 30 tracks active I'm setting ASIO drivers at about 14 msec 1536 samples, when I minimize Sonar, I can reduce settings to 8 msec 768 samples without pops.   The card is a Nvidia Quadro 280 with the latest drivers.  It's a 64 mb card. Kind of scrawny!  No other symptoms other than this. Anyone hear of a bad card causing a problem with dropouts?

Yup, one of our old tech's here was getting huge latency spikes on his home machine. Come to find out his Geforce 460 was throwing huge spikes with his particular cpu/motherboard combo. Unsolvable without swapping hardware. A lot of the PCI buses are bridged into the PCI-e controllers now too, which can cause issues. Same with how the USB controllers are tied into the system and their timing in relation to the PCI-e bus.
 
Run a latency checker application and see if you get consistent spikes in a regular interval. Sometimes it's the hardware but other times it's the bundled software that comes a long with the hardware.

Thanks Seth, I'll run a latency checker.

In particular, older video cards often cause DPC latency issues with newer OS.
ie:  I had a GTX 560Ti that I was going to move to my new machine (Win8x64).
Experienced DPC latency spikes...
The solution was to replace it with a (new) 660Ti (no DPC latency issues)

Jim Roseberry
In particular, older video cards often cause DPC latency issues with newer OS.
ie:  I had a GTX 560Ti that I was going to move to my new machine (Win8x64).
Experienced DPC latency spikes...
The solution was to replace it with a (new) 660Ti (no DPC latency issues)

Well I know not to upgrade my home system to W8 now...

Just a note - I'm sure many people already know this, but DPC Latency Checker currently does not report accurate results for Win8.

Seth Kellogg [Cakewalk]

Jim Roseberry
In particular, older video cards often cause DPC latency issues with newer OS.
ie:  I had a GTX 560Ti that I was going to move to my new machine (Win8x64).
Experienced DPC latency spikes...
The solution was to replace it with a (new) 660Ti (no DPC latency issues)

Well I know not to upgrade my home system to W8 now...

I had one of my two $400+ video cards on my Windows 8 box go belly up, and instead of replacing it, I went with the on-board graphics, and bought a nice shiny new 46" HDTV with the refund money - that now is my main computer display.  The on-board graphics drives a 32" HDTV that used to be my main display - so I have 2 nice big monitors, and ZERO problems with using the on-board graphics and X2a on Win 8.
 
Bob Bone
 

Not just the card, but the driver. See this older post:
 
https://forums.geforce.com/default/topic/505985/285-62-driver-firewire-audio-problem-audio-distortion-with-new-driver/

Well then, I guess it's not just a coincidence that this all started when I moved from XP to W8!.. I've since switched to 7 (thank you Mr. Bone!) hoping it was just an 8 glitch... Bob it looks like the graphics card could be the problem we were trying to track down a few months ago.  Hope so.  Thanks all.

@junedrive - Twas my pleasure to assist - I have learned and continue to learn a LOT from folks here in the forum, so am happy to give back when I can.
 
VERY happy you have that set of trauma sorted out for you - nice to hear someone is stable and happy.
 
Bob Bone