LinuxMusicians

You could try the tool irqbalance and do the following:
Contrary to the standard --oneshot option which practically does nothing on my system since it applies only once, running it directly as superuser proves fruitful. Make sure the following outputs false:
You can get an xrun-free system without SCHED_FIFO (Realtime), just that you would have to live with loose settings. I'm pretty sure -p512 -n3 does alright, since we raise the buffer even when not needed (not an USB device). 3 periods/buffer appear to be the only sane way to get sane response from onboard audio chips like mine, so discrete cards like yours would do much better.

schivmeister wrote:You can get an xrun-free system without SCHED_FIFO (Realtime)

Yes I'm gonna explore that first.

On the irq issue, first I'm gonna play with the hardware.

Thanks.