Latency  (yet again)

You have it right, Scantee.

If the PCI latency is too high for your ASIO buffer settings, it will be a source (not necessarily the only one) of dropouts. The lower you want to set your ASIO buffer settings, the lower the PCI latency needs to be. The total latency will be the sum of all the configured latencies of devices that have higher priority than your soundcard. I’m not sure how to tell what the priorities are, perhaps someone here can clue us in on that.

The excellent link above to the PCI intro alludes to a “maximum latency”, which unfortunately isn’t shown by either of the two programs we have – they show only the minimum latency. In case you’re confused, it’s like this:

maximum latency: the biggest latency the given device can tolerate. Lower values means higher priority.
minimum latency: the biggest latency the device will impose on the rest of the system – that is, it will always give up the PCI bus after this amount of time if anyone else wants it.

The PCI bus frequency is 33MHz (or 66, don’t know how popular that is yet). So, a min latency of 255 would mean 7 ms of AUDIO latency caused by just one device on the PCI bus (and the PCI bus latency is NOT the only factor, and often not even the main factor, as Bubbagump alludes to above.)

A PCI latency of 32 is about a millisecond, so going below that is probably going to yield diminishing returns. Hopefully, the soundcard has the highest priority. If so, then I was correct that only the highest PCI latency number matters. If it’s the second highest, then you add the highest latency to whatever the latency is for the device that has a higher priority. And so on, if it’s the third or greater priority.

TG, perhaps you have a 66 MHz PCI bus, which means your video card could only hog the PCI bus for 3.5 ms. Assuming your soundcard has highest priority and the drivers are extremely well written, then what you say is possible within my understanding of the facts.