Computer Hardware Help → Re: [motherboard] Checking Interruption of Realtime Processes?

This is probably happening at the HW level, and the usual utilities probably won't be much of a help there. I'd think a scope and a logic analyzer would be needed to solve this (and you should have those ) but you would also need to know the ins and outs of that mobo, including the chips and buses. (which you probably don't)

I'm not sure what you've done -- the first thing I'd look is all the event logs -- more often than not, if there is an issue, something will be there.

Based on the symptoms, something probably hogs some bus, or some other critical resource for an excessive amount of time, and without the necessary knowledge, pinpointing the root cause is not going to be easy.

In any case, since you have 2 identical mobos, you can exchange everything that removable and verify that they work fine in the other mobo, or not. At some point you either find a defective part, or left with the mobo, and since you've tried everything else, the mobo must be defective.

I agree with aurgathor. Swap the MBs and see if the problem stays or moves with it. That seems like the best and easiest thing to do at this point.

For one thing, this second system is a 'clone' of the first system I built in 2008 based on the DQ6 board. As I recall, I was unable to complete a clean install with Windows setup on the second system due to some failure or BSOD occuring, so I cloned the drive and set it up that way. All the memory tests good with MEMTEST86 and the system passed all the diagnostics I could find to test with.
I think aurgathor has a point: this is probably some low level hardware problem. I also replaced all the plugin components, such as sound and video cards, but the problem continues.
Swapping the mainboards is about the only thing I did not do. I'm reluctant to mess with my editing workstation, which is my 'bread and butter' machine.
The problem varies depending on several factors which have been observed but may only be correlations not causes:
System behavior is worse after booting up from a powered off state--system off for a day or more. Upon bootup, severe problems with system pausing with multimedia operations. Seems to clear up after about 30 days of 24/7 power on state.
Windows bootup is inconsistent. Sometimes system is behaving well, but then I restart Windows and it behaves poorly until I restart again.
I'm not sure what the problem is, but this motherboard was purchased from a previous owner on eBay in 2009. Maybe the owner did not disclose that there was a subtle problem.

Did you look into the event log?

Also, if it blue screens and dumps core, the .dmp file can be analyzed, and more often than not, that can help you to determine what's wrong.

You can also try installing Linux on it for troubleshooting. (it's more verbose, and may just tell you that xyz malfunctions)

Personally, if I can't fix something in a few months, or at least figure out what's wrong with it -- then I usually just stop wasting my time on it.